I don't disagree with providing feedback, but to "hate on" something is very different than providing feedback or constructive criticism. And of all things, more so art than anything else. Art is someone's personal expression. To "hate on" it is implicitly an attempt to invalidate that person's expression, if that were even possible. Are you being a judge of what someone should or shouldn't be expressing?
Per the author's "not my cup of tea" comment, I do believe that is actually a better approach. Because you are simply expressing that it's not something that you connect with/enjoy/appreciate/etc. and making your comments about yourself. When you "hate on" someone's art, you're completely missing the fact that your strong feelings are _yours_ and that the artist's expression is completely independent of that (whether others share your sentiment towards the work or not).