Honestly, considering that people praise their early albums so much for being so "experimental" I think a lot of that was outside influence. I mean, yes, we know that they were specifically told by the label that FII should just be crammed with "potential singles" and were forced into a more radio friendly direction, which was what gave it its distinct sound. But just because it was so harsh and forceful for that particular album doesn't mean that wasn't the case for their other albums too.
While they had relative freedom on Awake, there was still some pressure for them to make singles, as well as a general push to go in a heavier direction. The only difference between that and FII is that with Awake, they didn't end up getting half of their songs flat out rejected.
Everything that came before, WDADU and I&W, that wasn't "experimentation" that was just the band developing and discovering their style, and their style is incredibly unique, even 30 years later.
I think the kind of experimentation and the things that were so unique and different about Awake and FII were a fluke, a result of outside tampering that really, the band never wanted in the first place.
As for SDOIT, the only reason I think THAT comes off as so experimental was because it was the first album that they created compeltely from scratch with Rudess, and it was his style that really poured through on it.
That's just how it comes off to me, honestly. The only instance where they CONSIDERED being truly experimental for the sheer sake of being experimental was before SDOIT when they were planning to make that album where different songs were about different cultures, and would stylistically have influences of those cultures in them. But that idea got scrapped, for better or for worse.