A Deus Ex Machina is a cop-out, My idea however is no Deus Ex Machina.
You, sir, need to pick an opinion and stick to it. Unless your problem is not lack of meaningful choice for the player or decisiveness on Bethesda's part, but the fact that supraphysical forces were involved?
I quote:
I was very disappointed when Bethesda said "instead of picking one lets go with them all"
How is this any different from what you are proposing? Bethesda would once again be picking them all. And then forgetting that they picked anything at all, and expecting us to believe it.
Had only one of the endings happened it would have caused much more turmoil. turmoil leads to more story options.
Skipping forward XXX years would also be robing us of "turmoil" and interactive story options, since Bethesda could never discuss anything within the years of the Emperor's rule or the years following it (since his/her identity would still be public memory). We're talking 100 years of history lost, if not more (given that the Emperor could be an elf that lives for 500 years).
Also you became the lord of the shivering isles and still ran around in caves in Oblivion.
Which was also out of place and generally boring. Even becoming head of a faction carries no meaning. At least with Sheo you have the excuse of being the crazy, spontaneous, unpredictable Daedra who's been known to wader the world messing with mortals.