As far as I am concerned you usually don't immerse yourself while playing, which makes it kinda easier to play along with unlikable characters, totally normal.
But from a perspective of a person who usually tries to immerse myself I can say that it's hard to be that easy going.
It also depends on how Developer executes scenes and character behaviour.
As for this case, well, I think it's totally legit that some players don't wanna do anything with Ayase , personally I am not into blackmail whether it's me who is doing that or others, usually it's a no go for me, unless it's executed in a way that makes character somewhat redeemable in my eyes (again it's subjective).
But also I don't agree with those who demands blackmail to be deleted, it's Dev's game after all, if you don't like a character and if it looks like she will be forced on you romantically just drop it. It's actually one of the reasons I am not a fan of harems, cause usually chars are forced on you romantically. Not sure it's the case here though, otherwise why all this point system?
And as for Ayase - I'd rather not get involved with her romantically if I had an option, untrustworthy.