As someone who created a language that's gotten some momentum in the past year [
http://julialang.org/] and also drew the short straw and ended up making the web site, I can say that core contributors to programming languages (especially scientific ones) seem not to be particularly interested in making pretty web pages. So I kept it as minimal as possible, starting from Tom Preston-Warner's blog [
http://tom.preston-werner.com].
Could we hire a designer? Sure. But that's so far down our list of priorities, it's not even funny. And who's going to pay for it? Also, even the time spent dealing with a designer (finding one, negotiating cost, signing contracts, providing feedback, etc.) is time I could be spending on making crucial design decisions, closing issues, improving core language functionality, and writing documentation. That's probably why more mature languages tend to have fancier websites. The Go guys are still super busy making Go awesome!
Even if we hired a designer who made a lovely site, then someone has to maintain it. Programming languages are living, evolving things, and their web sites change. You know what's worse than a bare bones web site? A fancy designer-made web site with a bunch of changes subsequently added by an amateur who doesn't know what the hell they're doing (me).
So for now, I think we'll keep it minimalist.