In response to blip #109077
@kamimatsu: I think the term for that is "psychological reactence"?
Basically, people don't like to be told that they can't have something, in this case it's seeing an asexual character have sex or be portrayed sexually. So the natural response is to make the character have sex anyway. Also in this case, since the reason seems unfair or completely arbitrary, it just feels like the only way to not be 'controlled' by the creator for a 'stupid reason' that 'makes no sense in the first place' is by rebelling and making it happen regardless.
In lamen's terms, just think of the classic situation where someone says not to do something and the other says "you don't own me!" and they proceed to do said thing.