Just because some useful techniques were removed and the physics were changed (Look, I summed up his entire post in one sentence!) does not mean the game won't be as competitive or as that it has less depth.
What these changes have done (hopefully, it's still early to tell for sure) is make many many more characters viable in competitive play. It's no longer a game of "I can wavedash and L-Cancel better than you, so I can win with Game+Watch against you're Marth." It's a game where you need to use a different skill set other than being able to time wave-dashes and mash out combos as quickly as your fingers can let you. Mind-games are going to be huge in Brawl with combos being harder to pull off, you're going to need to fake your opponent into a mistake.
Dash-Dancing is still in the game, it can still fake-out your opponent, it IS a very small movement distance back and forth. In the end, I feel this is a matter of taste, than of anything meaningful actually being removed from the game, it's still there, just in a different form. Fast-Falling is the same argument, it's still there, but modified. It ties in with the whole game being slowed down to a speed between Melee and 64.
A more defensive game (if you're correct) doesn't mean it's worse, it means it's different. I, for one, am very happy that Wavedashing has been removed. I felt that Smash Bros 64 was a better game because you didn't need to rely on a broken game mechanic to succeed (actually, Z-canceling, but it was much easier to do than Wave-Dashing and thus, anyone could learn it in a few tries). You're right though, many approaching options have been removed... But, while some options have been removed, other options have been added. In other words, options that were removed BECAUSE of Wave-Dashing are now viable because it is gone.
Throws not being as powerful as they are in 64, and not being as weak and 'guaranteed' combo starters as they work in Melee is a change, not a detriment. And it's one I think is fair. The point of a throw should be to move your opponent out of attacking range, but it should never be so devastating as to kill someone at semi-low percentages or set them up into a guaranteed bashing. It's a defensive maneuver this time around, and that's a change that isn't necessarily a bad thing.
I don't know what your problem is with DI exactly... so you survive a little longer depending on who you are and who you're playing against, Power Characters like Ike can KO at <50%, weaker characters like Fox need to do upwards of 125% for dependable killing blows... this seems like a balance issue to me, and one that's long overdue. Fox, with his unimaginable speed and dexterity, should NEVER have had the ability to do a killing blow at less than 125%!!! This is a balance issue, and has been addressed in the correct manner. Play as Marth, and you're pulling off killing blows around 100%, just like common-sense game-balance would dictate!
You are right that character match-ups will be very important, but that should have always been the case!!! A game with 39 playable fighters should have more than 4-8 competitive characters! At least HALF of the characters should be able to compete in high-level play, that's a MINIMUIM demand, and Brawl appears to have met that demand.
Mismatched movesets is a bogus argument. Your Luigi example is a prime example of why the balance in Melee was so poor. Some characters were limited to a very few attack options, Luigi always having to deal with sending his opponent sky-high was great from a stylistic point of view, but limited his attacking potential. The movesets in Brawl are almost identical for most of the characters in the game, and the new characters have sets of moves that I'm more than happy with. Pit's B moves are a bit of a WTF, but that's one instance out of 39... You need to go more in-depth with this argument for it to hold any bearing at all.
Diminishing returns ties in with the higher-percentage kills. It will either make no difference at the competitive level, or it will have a huge effect on competitive strategies and styles trying to use it to it's full potential. Again, not a bad thing, just different.
Crouch-Canceling ties in with the whole argument that you simply need a new strategy when playing brawl, some options are removed with it, others are made viable. The new air-dodge system is fine. Ledge-Guarding is just as easy as it was in Melee and 64. Power-Shielding may be more powerful, I've noticed almost no difference in actual gameplay from my experience playing so far.
Tripping is a garbage addition to the game, but happens so infrequently that it probably won't have a huge impact on competitive play. I'll agree that it's unfair and one of the worst implementations in any fighting game ever. I don't agree that it will be the paria that kills Brawl, we'll all learn to suck it up and deal with it, and we'll move on.
All in all, I just want to wrap up by stating that removal of advanced techniques =/= less competitive play. In fact, it INCREASES the competitive play by allowing more players to compete. When the focus is on timing of moves and mind-games ala SSB64 rather than advanced techniques and combos ala Melee, more players are able to compete at a high level. Thus your entire argument can be flipped around to state that "Due to the removal of some of the advanced techniques from Melee, Brawl will become a MORE competitive game as more players will be able to compete with the best."
Consider it so.
just name the game super wavedashing bros. because wavedashing is more important than anything else. without wavedashing the game is just random luck drawn out of a hat and takes no skill to play.
But I DO know that SSB64 was very competitive and there was no wave-dashing. And the loss of L-Canceling helps to balance certain characters, and was an obligatory button-mash to begin with, not very "skillful". Wavedashing did INDEED take skill, but just because it's gone doesn't mean the game has less options available to you. With the removal of wave-dashing, all of the options that wave-dashing removed (and yes, wave-dashing DID remove options, you had to adapt to playing a good wave-dasher and could no longer use some of the openings available to you against a non-wavedasher). Besides, more options =/= more competitive play. You increase competitiveness by simplifying a game. You don't need LESS skill, you need a DIFFERENT skill-set! It's not all about lightning-quick button-mashing. It's now about positioning, priority of attacks, timing and mind-games (ala SSB64). The fact that MORE players (oh yeah, and did I mention... CHARACTERS?!) are going to be able to compete at a high level than could compete in Melee is a GOOD thing! 
