I was skimming through this thread, and wasn't sure if this was a point someone made, but if you think back on one of the Street Fighter 2 games (Turbo, was it?) Being able to cancel an attack into another attack to string true combos was actually a glitch due to programming oversight. However, it worked so well from a gameplay standpoint that the glitch was kept in as an actual gameplay mechanic for not just the rest of the series, but for other fighters that followed.
What Nintendo could have done was take mechanics that were received well in competitive play, and kept them in (dash-dancing and L-canceling coming to mind). I can understand why wavedashing wouldn't make it in due to the changed air dodge mechanic, but I digress. I do understand Nintendo (more specifically, Sakurai) wanting the game to appeal to casual players too, but to remove simple mechanics that even beginners can understand (dash-dancing and L-canceling) seems like a step back. It didn't work well for Brawl, so why would it work for Smash 4, especially now that the speed of the game is increased and tripping removed, making dash-dancing a very viable option, and the increased fall speed means L-canceling would be very valuable to characters who fall to the ground before any of their aerials finished their animation.
Just my two cents... and a pie.