I think one of the important things to remember about brawl is that simplicity was at its core. The purpose was that you didnt need to remember button mashing combos to be good at the game, it was assumed that you were in control of your character, and it was the mind games that really played into who the best player was.
Let me preface this by saying that although I wasnt ever as good at the game as Plairnkk by a long shot, I was pretty good at these techniques, and from a subjective standpoint i was sad to see all my practice go down the drain, but from an objective standpoint, here is what i think:
L Cancelling being gone --- Good. It isnt like you ever *want* to have more lag. Why not just auto L cancel? As I say, I believe the core of the game is that you are in control of your character, and being good is really knowing WHAT happens when you do these moves, and how to react. and then it becomes a mind game.
Jump cancelling gone--- Good...kind of. Before you needed to jump, and then CANCEL the jump and do an upsmash, clearly they didnt mean for you to upsmash while running. Now you can just Cstick the smash. this is good because you shouldnt need to learn a technique to do this, either they should not have it, or they should have it, and it should be easy to do. I actually think the whole point behind running is that you CANT smash, just like how you cant shoot when you are running in FPSes most of the time. However i realize how limiting this is, but if they hadnt gotten rid of wavedashing, this wouldnt be a problem...which leads me into my next point...
Wavedashing--- Wavedashing in its previous form was stupid. Dodge diagonally into the ground? give me a break. I think that they should have implemented somethign to replace WDing, because the lack of it is definatly noticable in gameplay. I cant move towards someone while facing backwards, I cant even play as characters with bad rolls. I thought the whole WD---> Dsmash stuff was kind of garbage in the old game, but SOMETHING should have replaced it, and the fact that nothing did means we are way better off when WDing was in the game.
Auto sweet spot--- nice try, it didnt work, why didnt it get cut? Ever try playing on corneria? KILL ME. It was an attempt at making the game easier for noobs since the good people can sweet spot whenever they want, but the thing is that for lots of characters it didnt help, and for the rest, it just took out mindgames. they should have just put a button in, like if you press B again after pressing up B, then it auto sweet spots, but if you dont press it, it doesnt.
dash dancing-- is stupid. at least thats my opinion...
Light shield--- well god **** it, at least let my shield COME OUT when i try to light shield. you know how often i get hit when i go to light shield and NO shield comes out? I dont get it. just stupid. Put light shield on L, regular shield on R, then it wont be an advanced technique anymore.
rolling for ledgeguarding--- GOOD, move in the right direction. holding on to an edge and abusing your invincibility frames to kill someone is stupid. I wish they had taken this out completely. You should only be able to edgehog if they dont hit you with their B up. yes, i know this would buff people with good spikes, but then they should just give other people things to even it out again.
directional Air dodge -- impartial. I think multi dodge is nice, and you have no idea how many times i died when i tried to tech and then bounced on the ground and air dodged off the edge as falco... however, the inability to use it for recovery is suckyness. another move that they should have replaced somehow like wavedashing, although i have no particular thought in my mind.
power shielding (reflector)--- extremely torn. anti camping is always good, but the thing is that its too hard to do, and its too overpowered if you are good at it. there is a reason some people were given reflectors and some werent. I guess im minorly in favor of it, but i could be convinced otherwise.
CC-- getting rid of this is stupid, it isnt like its hard to do... and it makes the game more dynamic.
inability to move after grabbing edge --- the worst thing about this game, period, end of story. you are basically screwed whenever you grab the edge, which is imposible to avoid since you have magnets attached to your hands. if i could change one thing, this is the one.