While my post is mainly geared towards my love of Brawl, keep in mind that I love 'em all. It's one of my favorite series to date.
I've been a long-time fan of this series, as well as really any Nintendo series. I've played 'em all for hours. Hours turning to days, days to weeks, and weeks to years. I still love '64, Melee, and Brawl. They are all great games, and I don't want to diss on any of them.
That being said, the moment I got Brawl, I've always liked it the best. While I did fancy such things as the new characters, there was more to it than that. I remember, after getting Brawl, going back to '64 for awhile. The only heavy I remember was DK. I remember, above all else, Mario's ability to kill everything. Ever. The game had great stages, and as far as I remember, was a standalone title over here in America at the time.
When Melee came out, most people switched to that. With a bigger roster, more gameplay modes, and different ways to utilize your gameplan(The ability to charge smashes, The L-dodge in air, Mario's cape, etc.). It was a step-up from '64 that many players loved.
And now we get to Brawl. Like I said before, I enjoy this one the best. While it is slower, the airdodge was changed, and many more things differ, I found it a nice change from it's predecessors.
The mechanics took my love, simply because not only are they slower(giving someone like me more time to think out my moves), it's easier to defend yourself. Flinching was reduced, meaning I could now escape someone's combo sooner, possibly even attacking them back. Also, recoveries were improved, so we could all get back to the stage easier. Seeing players live to 200%+ is amazing. One more thing about the "slow-ness": I've had some breathtaking exchanges because, simply, both of us(Enemy, me) predicted each other. In Melee or '64, it probably wouldn't have lasted as long. I loved Super-Armor. Seriously. Hitting somebody with that always feels good.
I felt the characters were improved. It's hard to ignore that Bowser's firebreath is actually useful. I remember it being insane to use in Melee simply because enemies went TOWARDS Bowser. Falco's game wasn't drastically changed(If I remember from Melee), having a shorter Bup and throwing his Bdown(Which I love to hit an enemy to cancel their attack). DK's Headbutting possibilities grew, Luigi became more separated from Mario, and the only real hardcore clone is still Ganon...Unfortunately. I could accept TLink, since he is really just a lighter version of Link, but even he plays differently.
Call me crazy, because although I like the stages in '64 the most, Brawl is my second. Pokefloats pisses me off, and I can't stand Big Blue in either of them. The reason I like '64 the best is probably because there is only one Battlefield knockoff. Can't say I actually dislike half the stages in Brawl like I do Melee. Don't even get me STARTED on Temple. That should NOT have been in Brawl.
I found the music in Brawl superior to it's predecessors. I'm not much of a music guy, though, so not much to say here.
Yes, SSE can be tedious. But it was a nice experience. I still enjoy playing it with friends on occasion. Classic and All Stars vastly remained the same(Except that, if you use a Heart Container in All Stars and go in the teleporter BEFORE it's done, it'll still go down to 0%). The Events and Break the Targets, though unfortunate, were definitely lacking. Boss Battle, honestly, was fun. Not gonna lie, I would go on there not because of the challenges, but because I found it fun.
I do believe that covers it. Single, Group, Music, Stages...Items. I like them more in Brawl if on low, but good god too many on any other setting. Liked the re-addition of Bumper, liked beating Sandbag in groups, etc. You guys probably don't care much for items, though.
All in all, looking at the evolution of the game, I do think Sakurai cares. He's changing the game through all installments, giving different gameplay and, all in all, a different experience for all titles. Although they all have the same rules, they feel different, and one person with amazing abilities from, say, Melee or Brawl will probably not transfer well into '64(Assuming A: Haven't practiced in...god knows how long B: Players don't strive to perfect their game in '64, since Melee/Brawl is their fancy). The series has really progressed, whether some like these changes or not. I embrace them with open arms, noticing that, by posts in this topic alone, others would probably spit on them if it were an object in our world.
I hope that Sakurai continues to change the game. As long as it's different from previous titles, it will give me something to not only look forward to, but master when it comes out. This is a simple lover of Smash Bros. saying, to all of you, that all of these titles are amazing. SSB4 may or may not appeal to you, as a player, but it will to others. Please, don't bash your fellow SSB brethren.
P.S. It's a real downer whenever I see "Brawl sucks, switch to Melee" or something similar to that. It's like talking to somebody who loves Super Mario World the most, while I love Donkey Kong Country 2 the most. These are obviously different from one another, but they are still both great freakin' platformers.
P.K. I apologize for posting such an enormous block of text when I could have easily said "Yeah, Sakurai cares", but after reading through the thread, I just had to.