Why are people so disrespectful?

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Two trending topics on Twitter at the moment are #SignsYoSonIsGay and #HowToTurnDownAUglyPerson.

Apart from both those topics being grammatically incorrect, they are viciously prejudiced.

I mean, so what if someone is a homosexual? That's their choice, and you should respect it.
And so what if someone who likes you is ugly? Why do looks even matter that much?

I'm so done with all this crap. Why are so many people (and I mean literally thousands, just search either of those tags on Twitter for proof) such disrespectful twits?
@Jamie
I don't think discrimination against other people is something that should be ignored. Anyway, I can't ignore it.