They're a reflection of the people who create them (rimshot).
Honestly, I blame Unix/Gnu (http://www.gnu.org/). Most programmers are command-line oriented and think GUIs are a distraction. It doesn't bother them that most newbies have no means of discovering features absent menus and suchlike, and that means design takes a backseat on their websites too.
I personally thought the go website was a lot better than most; at least it's (semantically) accessible, even if it's cartoonish.
I agree with you, and would add that the precursor to the modern full-featured browser-based WWW was a CLI-based web (Lynx et. all), whereby the only means of formatting text were akin to what you get out of a word processor (linebreaks, bold, italics, etc.).
Also, most programmers (like those making the languages) aren't designers, and when they try to be, very bad things can happen[1]. Could they hire a designer? Probably not, seeing as most of those projects are FOSS, and the maintainers get paid nothing for their efforts.
There's also the fact that the maintainers of those languages, and likely a majority of the users, would prefer development efforts be focused on the language itself and not its website.
Honestly, I blame Unix/Gnu (http://www.gnu.org/). Most programmers are command-line oriented and think GUIs are a distraction. It doesn't bother them that most newbies have no means of discovering features absent menus and suchlike, and that means design takes a backseat on their websites too.
I personally thought the go website was a lot better than most; at least it's (semantically) accessible, even if it's cartoonish.