Lots of fans complained about Sarah dying offscreen before
T3, and
tons complained about Judgment Day happening, along with the Terminator's ambiguous line that it was "inevitable". (As in inevitable in
any timeline, or just by that point of
that day, when the Skynet virus was already all over the place, and his mission was to keep them alive, not to stop it?) There was also lots of crap to be had about Superman abandoning Lois and the kid he didn't know they had for several years in
Superman Returns, as well as Scott's abrupt and meaningless death in
The Last Stand. And when James T. Kirk died being crushed by a bridge, while saving an entire inhabited world? To this day, Trekkers complain that he didn't at least go down on the bridge of a ship, the fact that he helped save a whole planet be damned. And then there's the classic example, where tons of people still reject
Alien3 entirely because it iced Newt and Hicks as a starting point.
So, yeah, fans have
definitely taken exception to unhappy sequel beginnings before.