People will always say hurtful things behind the relative safety of anonymity that the internet provides. I've always found it somewhat fascinating how they go about doing it though. I believe people will take whatever kind of injustice they perceive and try to make a concentrated attempt to argue against it in the strongest way they can. Which ends up being in the form of the easiest insults one can think of and throw at a person. The fervor over Mica is very similar to the case of The People vs Jeremy and Matt from not too long ago. I surmise that most people didn't like Matt and Jeremy because they were essentially "nobodies" to the majority of the audience and they got a job working at a place I'm sure a lot of people here would also love to work. So they saw them as interlopers on their own impossible to fulfill fantasies and internally(and sometimes externally) applied a lot of unrealistic hate towards people they didn't know and refused to give a chance to. I assume that a large portion of the audience are white males, and as Jeremy and Matt are as well, they can't really make sexist and racist jokes towards them. Most insults were just "They aren't funny! and "they're trying too hard!". In regards to Lindsey, as well as others outside AH like Meg and Ashley, they are also seen as interlopers as well since they're connected to people at RT/AH through their direct relationships. Although this doesn't make sense with Lindsey as she was at RT before Michael was(IIRC), but maybe it was applied to her when position in AH grew larger as well as, in absolutely no offense meant to her, people's hangups over her physique and attractiveness. Anyway, as they are seen as interlopers as well, insults must be made and the easiest way to insult these people is to imply or outright assert that their sexual organs are the only reason they are at RT/AH. For Mica, most negative comments regarded the idea that her only reason for being at RT was because of her connection to her famous father. So she is easily seen as another interloper to these people and insulting someone as a women is only slightly harder than insulting someone as a non-white person. People will take the easiest route to insult someone if they feel "wronged" and have the luxury of remaining anonymous while doing so. As a result, I'd like to think that there aren't as many people here that are actually as sexist and racist as they seem at face value, but are spoiled by anonymity and self-induced outrage.

Also, this is not intended as an excuse for their behavior, but just one person's possible explanation.