In brawl the only "dash dance" you could do was a really tiny, fast one. In melee the dash dance was a lot longer.
There is actually a new way of Dash Dancing to make it match the melee length, but is a few frames slower. It is a series of foxtrots. Since you could fox trot pretty rapidly, one could foxtrot > foxtrot again (but this time do the short DD to face the other way) > foxtrot > repeat. So technically, this makes Dash Dancing harder to do in Brawl because you would need quicker movements, but since tripping exists no one really wants to do that... or even dash in the first place.
On the note of Lucario, this is a very good buff. I know a lot of you were expecting a hitbox, but length works too. (Im not sure why people think Sakurai would even take stuff from P:M, a modded version of Brawl. That makes as much sense of him taking out stuff from Brawl+ or -... and yes I know P:M is bigger and all, but the idea is still rediculous.) Lucario was good in the Brawl, I wonder how good he will be in this one. So far from what I've seen, the characters have gotten buffs in the right places/movesets (sheild breaker was an okay buff, its only a problem because we all know Marth to be good, if he was bad... people would be complaining how it would be a bad buff). Hopefully this game is more balanced than the rest, hopefully even more than 64 (but I doubt it)