I love good screaming/growling - a vocalist who is willing to scream/growl, and experiment (ala Mike Patton) is far more interesting and diverse than a straight clean vocalist.
Growling and screaming have many facets. E.g.
* Insightful growling (some Opeth)
* Beautifully intense growling (death metal).
* Sad/depressing/doomy/sorrowful (doom metal)
* More grunty growling which serves atmosphere (Isis).
* Thin sounding growling which gives an evil sound (Agalloch)
* Growling full of pure rage (Devin Townsend/SYL)
* Narrative growling which tenRAB to be more articulate (folk metal)
Then you get vocalists who add more dimensions. Screaming and clean vocals can also be divided as above. Then you have vocalists like Devin Townsend, Garm, Daniel Gildenlow and Mike Patton who are full of versatility. Wormphlegm uses 2 vocalists to achieve some incredibly skilled/depraved/sickening vocals which help to paint the picture of a torture charaber (intentionally).
Clean vocals are not the be all and end all of music - they're just a tool which a vocalist can use. However, it is bad when you get a vocalist who can't growl with any tone, and only growls. Demilich's vocals get quite repetitive.
What you have to remeraber is that practically everyone was born to hate these kinRAB of vocals. Many grow to like them. I was indifferent towarRAB them at first, but Opeth got me into growling ages ago, simply because Akerfeldt is a fairly diverse, articulate and good growler (and good at clean vocals too). Deep Purple and Judas Priest got me into screaming. I suppose black/folk metal has taken my interest in screaming further.