The reason why defensive options are so good in this game is probably due to two things:
Items, and 4-8 Player Smash.
If you use the above two reasons to determine why defensive options in this game are so good, it makes a lot of sense. It would explain why shield dropping/airdodging is almost instantaneous, why most rolls cover more distance (and at a faster speed) than before, and why shields regenerate at a rapid pace. Sakurai did all of this to further glorify his game as a party game, and additionally, lower the skill floor to better allow players of all ages to have a chance at winning in Smash 4. And regarding the two aforementioned points, is there anything wrong with his views? No, not really.
However, the problem here is that while these defensive options being so potent is that, while they are optimal for matches with items and 4-8 Player Smash, they become a bit too potent within other areas in the game. In particular, 1v1 matches, and online matches. For online matches, the main issue here is that if you or your opponent don't have a decent internet connection, roll spamming just becomes silly with online lag. As for 1v1 matches, better defensive options don't horribly askew risk/reward in a sense that they will always give you a chance to punish your opponent while you are using a defensive option. Competitive players will always have an edge in that they will be more likely to predict rolls, shieldgrabs, airdodges, and so forth. Despite this, predictions and human reactions can only go so far, as matches involve two players trying to outsmart eachother as opposed to just one.
With better defensive options, while it might not break the foundation of risk/reward in a competitive match (specifically reward), it does do one thing: defensive options have less risk attached to them. I don't think anyone can really deny that defensive options in this game are stronger in comparison to the rest of the series. And yes, while they can still be punished and predicted, it does lower the window of opportunity of when and how they can be punished. Slower characters in particular will have a harder time punishing these options (thankfully the average character speed of this game has been amped up), rolling away from your opponent becomes a much safer option to reset the pace of the match back to neutral, instantaneous shield dropping allows you to defend against an aggressive opponent more efficiently (such as opponents trying to empty jump -> grab against you can get jabbed/utilted in the face now), and so forth.
This isn't a game breaking problem. No, far from it actually. Though it does raise the potential of how long matches can be drawn out. Safer defensive options -> More success in regards to escaping a disadvantageous situation -> More times where the pace of the match is in the neutral state -> longer matches overall. It promotes more chances where players aren't really actively engaging eachother, as it allocates more time being placed in players trying to return safely to neutral as it helps them win. Usually, this doesn't take away the excitement from players actually participating in the match, though it can. But it does make a good margin of people watching the match feel more bored watching the match because it takes longer/competitive players are more likely to use tactics to put themselves in safer positions. And both of these things aren't exactly great for the overall competitive lifespan of a game, and the former being a reason why some competitive players opt for playing 2 stock matches as opposed to 3.
Sakurai did try to balance defensive options as to not make them insanely potent. He did so using three methods: more shield damage, universal airdodge landing lag, and better grabs. Sadly, the shield damage is mostly negated with how fast shields regenerate. The other two changes have a much more immediate effect though. Airdodging is indeed less safe in this game in comparison to Brawl, and that is a good thing. And better grabs, while great for countering the improved shielding and rolling in this game, is half of the very reason why Smash 4's metagame is so grab-centric. Improved defensive options, with improved grabs to counter them. It is nice that such an option exists to counter such a potent aspect in Smash 4's current metagame, though it leads to a certain over-reliance on this option to yield the most success in countering said defensive options, as well as shortening the amount of time a match lasts.
Thus with all of these reasons combined, we have discovered why and how Smash 4 is so defensive and grab-centric overall, as well as why some players are dissatisfied with how Smash 4 currently plays.
So then, that's fine and dandy and all, but where does that lead us? My personal opinion is that while the defensive options of Smash 4 can be tweaked an improved upon, it is still an excellent game to play. Both casually and competitively. In regards to how I would want the defensive aspects of Smash 4 to be tweaked though, I feel as though seeking examples from previous games in the series isn't the way to go, however. Such as more shieldstun, which would indeed improve aggressive play in a 1v1 match, would have repercussions within other areas of the game. Namely the two things I stated in the opening of this post: Items, and 4-8 Player Smash. Adding more shieldstun would probably go against Sakurai's emphasis on Smash being centered around these two modes. For example, some items deal a TON of shield damage. Add more shieldstun on top of this, and a player would probably find themself with a broken shield within a second or two. And this can lead to the dissatisfaction of casual players playing the game. So then, if there were adjustments to be made to how Smash 4 handles defensive options, it would probably coincide with Sakurai's views on how the game "should be played".
One such example, which I have mentioned in a previous topic, would be increasing shielddrop lag.
With more shielddrop lag, it makes it to where defensive options while shielding are somewhat limited, and offense against a shielding opponent becomes improved. More pokes become safer against a shielding opponent, and the shielding opponent now has less opportunities in which they can punish a player who is attacking them (unless they perfect shield against them). This allows for more opportunities to be aggressive in a 1v1 competitive environment, and it doesn't really hinder item and 8 player matches as you can still roll/jump/grab out of shield. And unlike shieldstun, shielddrop lag has a universal timer attached to it (I think?), meaning that it becomes a lot easier to know when your poking options are safe against the majority of the cast. Plus it coincides with how Sakurai gave a universal landing lag on airdodges.
There are other things that could improve Smash 4 in regards to toning down defensive options/grabs, but ultimately, it is what it is. Smash 4 has shown that it can be a good competitive gave even if it is more oriented towards defense/grabbing, and the development team have shown that they are willing to patch the game for the sake of balance (at least balance in their eyes anyways). So while competitive players will have to adapt to the new mechanics Smash 4 has, it is still a very fun game, and that is what counts. Improvements can always be made to the game's mechanics, sure, but Smash 4's reliance of defensive options and grabs only really pose a problem to laggy online play. Competitive players, on the other hand, will be able to handle it...even if it leaves a bit of a sour taste in some competitive players' mouths. So while there might not be much we can do about it, we can always adapt.
