I really cant think offhand (although it is 5:30 am here so thinking isn't a strong point right now, if ever) of any musicians who dont compose (outside of classical music), it is part of being a musician.
I can. They're called cover bands. Or highschoolers. Thats besides the point though, I think. Many musicians do compose and I respect them for that. But I definetly think playing music and writing music needs to be seperated. Today, many people who know nothing about music would argue that someone who composes music on a computer is not a 'talented' musician. Among these people, playing music actually gets more respect than composing, which is asanine.

And although playing virtuoso peices commands respect, it's the hard work that deserves respect and it says nothing about musical talent. I wouldn't call a virtuoso pianist or guitarist a talented musician. I'd say they were a skilled guitar/piano player. I think there is a big difference between the two.