for those of you dissatisfied with static factions, if you'll excuse the shameless self promotion, i'm kinda working on fixing that (see my sig)
i dont see the problem. you make a statement based on an assumption, yet you are bemused by being asked to "put your money where your mouth is"? if we're going that route, i say the sky is green, and the burden of proof is on you to show me that it is in fact blue. catch my drift?
i've run an MMO server before. i've even (mostly) customized a MUD. i know the numbers involved. i disagree that morrowind is too different from "mmo of your choice here" to make a comparison. they are different, yes, but this does not mean you can not make a comparison, especially about something as concrete as amount of content. morrowind is quite different than, say, final fantasy... yet we can compare the amount of content (btw, morrowind has more than most - if not all - in that series)
player involvement isnt quite content. player involvement is EXPERIENCING the content. and even as static as vanilla morrowind is, it is still more dynamic than just about any MMO you care to name. all the problems you listed for morrowind can easily be applied to MMOs. even worse really. only things on a leveled list respawn in morrowind (unless scripted to do otherwise, such as the gateway haunt.) in most MMOs, to respawn a boss, just leave the dungeon and go back in. let me put it in these terms. everyone playing morrowind is playing a mmo, they are just instanced to their own game, rather than having a lobby or overworld to interact with others in. it's the same thing.
so i ask again for proof that morrowind has less content than an mmo, any mmo. otherwise, you're claiming that the sky is green.