>>4522609>this was just Nintendo starting to get the formula for maximum appeal down
Smash was made by Hal, was not a big budget title. Smash is very similar to Kirby Super Star, in fact Smash games feel like a fighting game version of KSS. The way your moveset differs if you press attack button, forward+attack button, dashing+attack, down+attack, it's the same as in Smash (down smash, forward smash, etc).
Smash obviously went ahead and implemented more specialized control mechanics like grabs, hitstun, cancels and so on.
I do think it became what it became because of the Nintendo characters, otherwise it would have been remembered as a weird JP only fighting game that nobody played until recently, like the custom robo series. But thanks to the famous characters it broke into the mainstream.
It wouldn't have lasted this much if the actual core game design wasn't good, though.
Like Kirby, the gameplay is extremely accessible for newcomers, but experienced players will floor them, skill ceiling goes high.