I personally like the sewers. Think about it..in real life..if you go down to a sewer, you really can't see much, even with a flashlight...you can HEAR things down there...squeeky rats, skittering bugs and the like...but can't really SEE them until they are right up on you nibbling your toes lol. So the unable to attack until they are right on top of you thing makes sense to me. When we had to go kill rats for the coins during that one event....(No I can't remember which one!) The gold soverigns and that? It was pretty easy...these slimes, yeah they hurt....ALOT! I go down there on my archer, easier to keep myself healed that way with healing rather then casting a spell cus I can heal and shoot at the same time. I lure a few off to the ladder and go up and down if I get too low, did die once but the healer is right there so it's not an issue.
I don't know why anyone would HUNT down there other then for events....just rats and froggies...and runnin through there isn't hard..it's very..sewer-like....so I don't think it needs to be changed at all.. maybe do something about the spawn in the water that can hit you but you can't hit....but again, I think that's realistic, for anyone that's actually been down in a sewer lol.