I hate them because they render manual configuration all but impossible. God help you if for some reason your plesk/cpanel decides to crash when you need to perform an urgent change to your server. If you can't get it restarted because the error occurred a million levels down the dependencies tree, on some obscure cipher list you lack the arcane knowledge to fix, you're screwed.
It's like cooking on someone else's kitchen. You may be an expert at handling the pots and the knives, but you'll have trouble finding where everything is stored first.
That's why I'm really enjoying Linode. Their barebones approach to server software seemed a bit lacking at first, but then I started appreciating the advantages of not having to deal with someone else's standards. Linode gives me a tabula rasa machine, hands me the most accessible documentation I have ever seen, and waves me on my merry way.??If something ever goes wrong, I'll know what to fix because I was the one who set it up.??Awesome.