Yup, have to agree. Smash is in it's own right great fun. But there are so many things to learn (movesets, items, stages) it takes a while for newcomers to get used to it.
It's an awesome game for me (and most of us here) because I (we) know Smash. But if you've never played an installment before...you won't get any fun if you play with people who know the game.
Towerfall, as you said, is much easier to learn and pick up. That's why I - and you - think it is currently the greatest local multiplayer game there this.
It's a shame, though, that not many people play the game...at least none of my friends are willing to give it a go -.-