What's the big deal with streaming music services?

Pandora, Spotify, Rdio, Beats, iTunes... there are so many streaming music services out there today and it seems there are many strong opinions about them as well. I'd like to know, as someone in their late 30's who actually hasn't done all that much serious streaming yet, what the differences are and why. Why "iTunes Radio sucks" (seems like everyone hates it)? What's so special about Spotify or Beats? I've used Pandora for ages, but it was just something that would passively play in the house on the Bose dock for background music. Today, I'd actually like to discover new music, new alternative and indie electric, things like Phantogram or Bonobo for instance. So I created an iTunes Radio station based on Phantogram and I hear music which is similar and it's great. I discover an artist I like and buy the song or just check them out later. Seems to work just fine. So what is the big deal in terms of the differences that have brought so many choices for services as well as consumer opinions? What am I missing out on? How is one better than the other?

Thank you for feedback.