To each his own, then, I guess. Even if you hated the first two Thor films, that's no reason to be so pessimistic about Ragnarok. You really can't use the previous movies in a franchise to judge the quality of future installments. Who would have thought that the X-Men series would have gone from the brilliance of X2 to the utterly awful "Last Stand" and "Origins"? Similarly, I'm not sure how many people expected Cap to go from the mediocrity of " The First Avenger" to the incredible "Winter Soldier". Just because the Thor franchise is currently hated on by a lot of people doesn't mean it will stay that way. If Civil War isn't as universally accepted as Winter Soldier, and if Ragnarok is amazing, then Cap could become the maligned franchise instead.
I think we should all be very excited about Ragnarok. I don't think Feige would have lied about it being the most important film in Phase 3. By the way, the film will be about Ragnarok, the end of the world. Of course it's going to be extremely dark. My only concern is that they shouldn't make it too dark (unlike, say, Man of Steel).