If you've found such people - great. In places I've worked it was different. And designers did exceptionally beautiful things which I really appreciate. I'm proud that I've worked with them, even if they left some mess to be cleaned.
There is some knowledge and experience needed in dealing with IE6, having CSS well organized, images optimized, adding even light JavaScript.
If I was hiring (I do not), I'd totally prefer to have two people who can together build something great, than look for one person and receive worse results.
And I'd prefer my people to do what they do best. The skillset required in designing rich graphics is different than coding.
If all someone knows is making pretty images in photoshop, they simply aren't web designers, they're print designers who dabble in the web, amateurs.
They're print designers but definitely not amateurs.
In the end, what really matters is that the client receives very high quality work and it is cost effective for the company. I understand that not every company works this way, but I have worked for and know some that do exactly this.
I don't really want to discuss it anymore, I feel we're repeating the same arguments over and over.
If you can't build me a complete cross browser HTML template, a skin, for a website, you aren't a web designer. That means you must know HTML, CSS, browser idiosyncrocies, and possibly some very light JavaScript. Developers should never even see a PSD file or worry about what it looks like in IE. That's a designers job.