That's why everyone should do it!! to avoid such disadvantages.
No, that's actually quite wrong.
There are certain characters whose wavedash is absolutely terrible, or not good enough to use it consistently.
C.Falcon, Link (I'm a Link main, don't argue it), Zelda, Peach, Bowser.
Sure, the majority of them are lower-tier, but that's not because they don't have good wavedashes.
Wavedashing is not nearly as important as you think, dude.
The only important, MUST LEARN technique was L Canceling, which isn't a glitch, since it's currently in the Brawl demo.
Also, Melee was very, very mindgame/metagame oriented, character match ups played a big part (usually), and out thinking your opponent was/is about 70% of a pro match.
Any pro will destroy you in Brawl on the first day, without advanced techniques, and probably even if you have items on, because they'll be able to out think you.