Oh, well, I never trusted Doctor Who to make a ton of sense, or to set up its endings particularly well. (For the most part, it still doesn't do that. The last three seasons have had a lot--a lot--of "Everybody lives!" endings, and every single Moffat-run season finale has involved somehow rewriting or reimagining the timeline of the season that preceded it. So I'm also a little tired of the device.) But once upon a time, I did trust it to care about its characters (even if 10 was an ass, which he of course was), care about what it was saying, have consequences for actions, and not undo anything that happened more than an episode or so in the past.
Anyway, I'd actually be cool with the illusory sacrifice if the suffering that was all for naught wasn't...60-70% of the past seven seasons. Irony's great, but I don't want to build a series on it. And Doctor Who in particular invites emotional investment.
Okay, sorry for my incredibly long-winded Doctor Who thoughts. This keeps happening, lately.
I think I at least get where your sense of betrayal is coming from, though--I feel that way about later seasons of Buffy.
I don't know what you're talking about. Season five of Buffy is great, and everyone knows that Buffy ended after season five.