In TES, one can make a single character that can do everything with maximum skill. And there is really no quests that are so enjoyable that I absolutely have to do them twice. And there is no group with social interactions, especially no romances, like in Baldurs Gate, Knights of the Old Republic, Neverwinter Nights, or Dragon Age. And no, not even in Morrowind there was much of a limitation about what you could do in one walkthrough - see my answer to the posting below. So what would be the point of ever creating a second character ?
Not that I havent played around with a lot of characters in Morrowind before settling down with my female Breton Atronarch do-it-all I played in Oblivion, too. And started a couple of characters in Oblivion before returning to my default. But after a while I always ended up disregarding every other character, simply because there was no reason to ever play a second character. Races dont have much influence and Breton has by far the most useful racial properties, anyway. And more importantly, they are both in Morrowind and Oblivion the most beautiful of the races, especially the female ones.
Despite that, I probably will do everything I can with one character (hopefully there will limitations like in MW).
Hu ?
Hardly.
You could reign all major guilds with one character if you were careful enough with the sequence of quest you did for Warriors and Thieves.
And if you did it early enough, in respect to the main questline, you could also join and lead the Priests ... thats the point were I actually hit the 2 months limit I have with every singleplayer game except Baldurs Gate 2, after which the game can be as good as it wants, I am simply bored by playing it - so after that I stopped playing and never finished the MW main questline. Oh well.
The Brotherhood, I think you could join them after you maxed all other guilds just fine. I never did that one, either. Kinda sad, I heard those are the best quests in Morrowind (and Oblivion). Oh well.
And you could only join one out of three houses. But they were not that super interesting that it really mattered anyway, plus if I remember correctly, only one offered you those houses you could only enter with levitation, so that choice was a nobrainer, too.
Thats all of the "limitations" I can recall from Morrowind (mind, I didnt played that one again, ever, once I got Oblivion, so my youngest experiences with MW are at least half a decade old).