I think CMS's are generic. They have a real template sort of feel. I can always tell when someone is using a CMS... easiest way is to look for the copyright at the bottom.

I wouldn't use one for my web design portfolio. That's kind of like saying, I'm a web designer, but I can't even design my own site.

Portfolios are fairly simple sites. They should be very easy to maintain, but they shouldn't look like a wordpress template.