I didn’t actually mind TZ as an idea, but it probably could be refined a bit better. I certainly wouldn’t call it “bad” for the game, though. Creating more farmable areas is a good thing, imo. What I would probably do differently is just make it a lobby toggle that sets all the zones in the game to TZ scaling, so you either play with it or not–electively.
I really don’t think hammerdins are that much of an issue, though. They are just a budget build that scales well, but they aren’t even the absolute or theoretical strongest. Again, their popularity is more a consequence of a bad game mechanic than them actually being more fun to play.
I don’t have much opinion on Mosaic either way because I haven’t played with it much and mostly only join multiplayer for rushing/trading, so it hasn’t exactly impacted my play experience either way. In other words, I’m not really contesting the opinions of people on the topic, for or against. I’m just indifferent about it.