Yeah, defaults are always tough to choose and we tend to default to what is in RHEL. That said, Ruby comes up a lot and we are actively working on a slick 1.9.x experience out of the box. In the meantime (I know it's a hassle) but we've built the underlying foundation to let you do what you want. For example:
http://bit.ly/HHp9aR
Also... if you wouldn't mind helping vote it up, that would help:
https://openshift.redhat.com/community/content/support-for-r...