I need to get this straight, you're tired of playing the hero, but disappointed when you're not treated as one at the end of the game?
Anyway, I agree with @CronoDragoon that the ending is quite realistic; none of the countries want a "freebaser" with that much power within their borders. And remember that we're only halfway through the inquistor's story (even though I think we'll experience the rest of it at least partly through someone else's perspective).
I like that we get "stabbed in the back." It felt very natural to me that Orlais and Ferelden would not be content with the status quo of the Inquisition. Considering the Inquisition ties to Orlais after Wicked Hearts, does it make sense that Ferelden would feel comfortable with the Inquisition essentially taking over some of its lands? Does it make sense for Orlais to be all right with it considering the Game? I understand the desire for acceptance, respect, reward, but its precisely the unfulfillment of that desire that can produce strong feelings towards the narrative. And the Inquisitor herself can voice those strong feelings, as you are given opportunities to be angry about your current lot in life. I was content with the speech my Inquisitor gave when she decided to disband the Inquisition, essentially telling the Council that she wouldn't let the Inquisition be turned into something else for someone else's purposes.
I didn't say it wasn't realistic. I actually did say that Trespasser told its story well, but I hated the outcome.
The impression "I lose" came from heaping it all up: I lose the arm, I lose my cool magical extra, I lose my organization and I lose against Solas, Ferelden and Orlais. On the meta-level, it feels like being discarded by the story because I'm no longer needed (and isn't that exactly what it is?), and the worst part is that I'm supposed to be content with that, again, on the meta level, because Bioware expects their stories to be emotionally satisfying. Well, I'm not satisfied.
You're correct in that such a drastic downturn can produce motivations, but then, it's the end of the Inquisitor's story, I'll get no opportunity to play out my dissatisfaction in-world. If I got to play the Inquisitor again, and were again locked into the hero template, it would feel out of character. That's the immediate reason why I was posting this just now.