You call them glitches. I call them techniques. The smashbros community generally defines what is broken or not through massive trial and error in major tournaments with lots of cash on the line. Usually if a technique upsets the balance of “The better player will always win”, it is removed. Right now, there is a big discussion about a technique called ‘wobbling’. It is an infinite combo that is relatively easy to do with the ice climbers. A player called Wobbles was able to use this technique and defeat players better than him and went on to win the most recent Evo tournament. He received much criticism and hate for it from many of his peers, but wobbling was not banned by the tournament rules. Therefore, he was technically not doing anything illegal. So you see, even still to this day the rules and glitches are under constant review to maintain the integrity of the game.
How this applies to our situation: This same community decided long ago that basic advanced techniques, such as the ones I use in our LAN, are not gamebreaking. They just provide opportunities that otherwise would have been unavailable. They are not hard to learn, and with a bit of practice can be incorporated into your game.
Although wavedashing specifically is out of Brawl, it already has similar techniques in it, and I fully intend to use them as best as I can once I get a copy to practice on.