Pretty much anything Imagine Dragons comes up with I'll like, and they're mainstream right? I like a few scattered songs here and there, but I rarely listen to mainstream music. I don't think there's anything wrong with it, per se... in my own opinion, I just find it generic. And they lyrics... wow. I usually don't pay attention to lyrics of a song but these ones are just... yikes. However, I think a lot of mainstream music has really catchy instrumentals. So if I went on YouTube and dug up the instrumental versions of these songs I'd like them :D
I haven't seen it really 'improving.' It seems similar to what it was years ago.