Nah. It is possible to make professional-quality, shiny, colorful graphics with GIMP if you know what you're doing. Sure, installing the non-default fonts (that is, not having a one-button install method) and configuring everything is what prevents most people from adopting it.

There are graphic designers who are graphic designers, and then there are web developers who are also graphic designers.

Have a look at what some "designers" are getting paid on sites like crowdSPRING.com and 99designs.com and it's pretty obvious that graphic designers who don't know code are fairly easy to find.

I think this has been why there's been such a backlash against the freelance sites by the brick-mortar "design only" firms.