Because you haven't heard them all.

Seriously though, I used to hate everything "techno", and that not only included trance, just everything with an electronic beat. It was all techno to me. But that's such a childish attitude.
There are genres I don't really like, but I still enjoy some of the songs, and I try to understand them: what they mean, how people are meant to listen to them, what emotions they're supposed to evoke. That's why I started
this thread. There are also many genres that I didn't really like because I didn't understand, but once I got them, I started liking them much more. My musical taste is always changing and expanding.
To me, music reflects life. Constricting your taste just means you're missing out on a part of life. I find in each type of music a different part of myself. I think limiting yourself is the only thing that should be called a "bad taste in music".
Trance is as similar to electro as hip-hop. Actually, some electronic dance music is closer to hip-hop than trance. And even within trance, there are many different sounds and emotions, and the only thing that binds them together is that they "entrance" you. Trance is influenced by a lot of genres. So is electronic dance music generally. There are so many electronic producers who add jazz, soul, elements. Many others add classical elements, and others add hip-hop elements. They all sound very different.
You can dislike certain artists, but believing that they represent an entire genre just shows that you have no idea how varied it is. I mean, I don't like Nicki Minaj or Ke$ha, but it would be ignorant of me to think they represent all contemporary pop music. Just like it would be ignorant of me to say that I hate hip-hop because it's too materialistic and degrades women. There's much more to hip-hop than that, and I absolutely love many aspects of it.