Well I don't rake through videos... for anything, really. I've watched few myself, and hardly have a library of videos showcasing all the things I like about (insert something here). Let's put it down to style, it really does avoid a meaningless argument.
I don't spam specific moves very often at all, either. I don't SHPKF to approach very often, as I just don't like spamming at all, and I like to preserve my PK fires and keep them as more of a surprise attack. More often then that I'll lunge at an enemy with a nAir and air dodge when I get reeealy close, and then either uTilt to start an aerial combo, or just sideTilt to knock them away to start another approach (or sometimes a mini-combo).
And I don't know what Brawl you're talking about, but I don't find the dAir hard to hit with AT ALL, especially when it's SH-d, as I said, because foes are completely sucked into it as Lucas sort of floats above the ground. I honestly find it to be one of the most RELIABLE ways to combo into an uTilt to then knock them into the air, so that Lucas can start breaking castles.
That said though, I haven't done extensive testing against EVERY single opponent. It may well be that this is only effective against a select few characters, but regardless I will not retract my claim the the dAir is one of Lucas' fundamental moves when used right. Even with the low damage, it doesn't matter. The important thing is just how ****ed effective it is for combo-ing into an uTilt, which is very important for initiating Lucas's epic aerial game.
Edit: Oh, I'd also like to add that I do realize that generally fAir is a much more useful move, but personally I like to avoid spamming it and using excessively for combos because of how **** good it is as a finisher. Using it less helps avoid degeneration and makes it more surprising when it is suddenly whipped out.