They were incredibly static on stage in those days, each member barely moving from their spot on stage. James also didn't interact with the crowd at all for the most part.
Subject to the limitations imposed by small stages at a couple places where I saw them on the I&W tour, this wasn't my experience at all. I think there's a lot of video that shows more movement back then than they've done at any point in the last 20 years -- particularly in the case of John Myung (and obviously, KM and MP were anchored, so we're only talking about JLB, JM and JP).
Yea, I've only seen a handful of videos from those days, but they were way more physical than now. In fact, I'd say they've been becoming less and less active on stage as time goes by. Minus JR (oddly), they mostly just stand there and make faces.
I don't know, for me there definitely was an arc to it. Some time around the time they turned more metal they also cranked up the stage antics a bit, but before that there was always a bit of a "Berklee recital" aspect to their concerts.
Maybe you've seen more than I have. And this is all relative, since DT are pretty tame compared to most bands, but FOR them, they seemed pretty active back in the day. I dunno. I just remember JM running around a lot more, JLB running around a lot more, and JP....well he's always been pretty tame.