I think a major problem with Ruby not being as popular as it should be is its poor support for Windows. This is not a good thing for a language that's supposed to be cross-platform.
You have to jump through all sorts of hoops to get it installed and even then not all Ruby scripts are compatible with Windows. For instance if you do a simple call in a command line program to clear the screen System("clear") it won't work for Windows which requires System("cls"). You have to look at the OS version and send the appropriate call.
There are other little gotachas like that all through out the system. Like some ruby gems require compilation and they are not written for Windows. Most Ruby programmer seem to be Unix/OS X people (I am) so they don't bother making their stuff work with an operating system they loath.
I know I don't write in Windows support because I'm sick of having to support substandard systems like IE. I have to spend so much time at work fixing Microsoft's buggy browser I'm not spending 80% of my time in Ruby writing fixes for Windows when I can have the app up and running in a fraction of the time.
Hence Windows based programmers look at Ruby as a "Mac elitist thing [they] don't want to waste time on." (An actual quote from a work buddy). And refuse to even look at it. I can't tell you how many Windows programmers I've spoken to over the 'net or at work that say they hate it and list all these reasons that don't even make sense. When I ask them if they have every used it the reply is usually either "I tried to install it and it was too much of a pain," "I tried it for a day but nothing worked right.", or just plain "No."
I personally think it's silly to hate an OS or computer or language but then again I've never been the fanboi type. I want to use what I like best and what does the job best for me. Right now that's Apples and OS X.