Are they good? I mean, we've got an Arcane Enchanter and Alchemy Lab in the Main Hall and they seem to do their job properly. Do those towers have anything special related to their job?

theyre just mainly to rp with
but the alchemy tower restocks some useful ingredients when the house resets after being away for 30 days, including a few bowls of the hyper rare powdered mammoth tusk

Not really. They do have closer, more convenient storage options, and are more aesthetically pleasing. I suppose they look more 'wizardly'. I like them, but have discovered I don't need them. Maybe if I was playing a character who was actually a mage, I might do them again. I think the ground floor rooms of the towers are pretty useless, just storage, and not even much of that.

I chose the alchemy tower for my current character just for the views and roof access, her actual alchemy table is in the main hall. lol