I think one of the main reason (AFAIK) we used "-rhel7" and "-centos7" suffixed for the images
was that we simply used one repository ("openshift/") and we needed to have a way to distinguish
between rhel7 and centos7 images.
Now, when we are pushing the images to "centos/" namespace on DockerHub, this is not longer required
I think, because "centos/ruby-22-centos7" sounds just weird :-)
images, we can relax the suffix.
Are there any other concerns or reasons why keeping the suffixes is bad other than it "looks weird" and it is