This is the problem with labels. You never really understand the true nature of a genre because most people want to pick it apart.
I think that art is freedom. Period. I think that trance music is a style/genre, but I wish it wasn't. Let me ask you this question: If labels weren't real, would you be asking this question?
On a grander scale I would have to say most people would say no. I think that music should just exist. Like the rain, or the sun. Some people like the sun, some people like the rain. I think that TYPE of NEW trance you are talking about likes to use the sidechain because it compresses around the bass note when it the gain in the sidechain pushed to its limits. I think the younger crowd likes to dance to it. It is just a trick, nothing more. The Chemical brothers did it, and they are still trance.
Is this trance, is that trance, why has trance changed? You ask. It hasn't changed, because it doesn't fit into the mold of what humans call "labels".
That is what I think about it, and I am sure you could feel obliged to disagree; I just want to see you free your mind.