Hmmm, besides John Romero taking away large chunks of Ion Storms finance (for no gain in the end because Daikatana sucked) and the fact they were in problems if no financial good game came onto the market? Also he might be a reputed dev. he was still on a new company; and in the shadow of Romero. We all know what crap Molyneux produced after he left Bull Frog as example...
And if Spector's vision could be reached; as you say WHY the amount of cutting in missions (moon, texas, mountain, UNATCO) and the remark he rather had 75% of the gamespace with more character immersion? If he was so powerfull in the dev. why didn't he just made it 75% and improved the characters? As you might have read in the plan they actually even made most NPC's and the way they responded on you that made the game the classic it became on the long way; it was not planned...
And ofcourse we all saw what happened with IW, when they HAVE the time and finance...