I wonder what limits or requirements we might place on geological oddities, climate oddities, weather oddities?
Talking out of my butthole here a bit, but these things along with creatures are setting. So maybe living in a world we don't fully understand with oddities isn't exactly a foreign thing, because our world is full of amazing creatures and fantastic sights, so I don't think it's much of a stretch to accept a different world with equally amazing creatures and sights.
BUT, I think we're less accepting of characters doing things without foreshadowing because readers understand characters. They are characters, with motivations and abilities that have logical reasons behind them. So when we read about a character doing something unreasonable, it's a lot easier to say "Hey, that's BS. I wouldn't have done something like that."
In Star Wars Episode 4, everyone understands why Han shot first, but does anyone care for an explanation of how the force really works?
In the Star Wars prequels, how many people really care about the inner workings of the Senate, trade embargoes, etc.? And how many people would have really liked a well thought out reason why the f#ck Padme just died? OR why Anikin just went all darkside at the flip of a switch?