The main thing about a fighting game is that it has to provide a portal for new players to a) be able to git gud, and b) be interested in gitting gud. Smash already does both of these things very well, likely because they want to do it well. Like it or not, the spammable moves make beginners feel good and make them want to play more and get better. When they reach higher levels of play, they realise that they can be more generally effective by using more clever strategies.
The competitive community is still always going to be important in any major fighting game, but Smash's casual audience is certainly not invaluable. I think the new online modes will really encourage a lot of players to try and get to a higher level of mastery which normally only the competitive community would try to reach.