Does anyone have a simple answer? I'm only just beginning to learn Ruby after being a PHP developer for about 4 years, and it seems clear that Ruby is the better language by some margin (not necessarily a better platform; I don't have enough experience to draw that conclusion). Ruby just makes so much more sense than PHP. The syntax just seems so well polished. In fact, it's probably the nicest language I'm yet to see (and I've spent time with at least 8 different modern programming languages). So far there's not a single bit of syntax or idiom that I'm not happy with.
Why isn't the take up as aggressive as it probably should be?