[sad]

Because:

You get the whole Java ecosystem at your fingers. It's faster than MRI (1.8.7ish) and a contender (maybe even faster now) against MRI 1.9.2. It interops with other JVM languages. It plays nicely with uptight IT departments (you only need to download the jars).

[epochwolf]

The 1.9.2 interpreter is YARV, not MRI: http://en.wikipedia.org/wiki/YARV

[sad]

YARV is the VM, it's still MRI (Matz's Ruby Interpreter)

[ssmoot]

Not that I've ever seen referenced. You don't really see the YARV name thrown a ton these days either I guess, but MRI means C-Ruby to most I think. YARV is a VM and from what I understand Matz had very little to do with it in the period leading up to 1.9.

Maybe it was behind the scenes, but the original status pages for YARV gave the impression it was a one man job up until it was official.