I always thought it was strange that they celebrated their 20th anniversary in 2005, since 99.999% of bands out there base their anniversaries, and corresponding tours, on what year their debut album came out, but I am sure we can guess whose idea that was.
This.
I also thought it was extremely weird especially considering they weren't even Dream Theater back then, and much more considering they didn't took off until '92 with I&W. I don't see it as wrong with the core band being there, but I'm on James side of the argument that it doesn't make sense now.
I disagree. When the band celebrated their 20th anniversary in 2005/2006, it was the anniversary of the band, not the debut album, and at the majority of the shows on that tour, they played something from each album, including Another Won from 1985/1986. Honestly, to me it makes a lot more sense to celebrate the band anniversary than an album anniversary, unless it's gonna be a focal point of the show, as Awake and SFaM are on the current tour. But when you're doing a retrospective tour, then the anniversary recognized should be the band's beginning point.
Not only that, but the whole "they weren't even Dream Theater back then" is not true. It was a name change - that's all - it's not even a situation of the guys being in Majesty, breaking up, and then everyone later getting back together aside from Chris Collins. Had that other band not already had the rights to the name Majesty, it's quite possible that's what DT would still be known as today.
That said, I can understand why a band like Rush has chosen to use 1974 as their starting point, since that is when Neil joined the band. But when a band has multiple lineup changes, as DT did, then I don't understand why the debut album should be considered the started date/year of the band's existence.