What's in a (CentOS) version number?

For free, I think that's not exactly the opinion of the engineers working on the company payroll. They are not just repacking free software made by hobbyist on their free time as your comment seems to imply. As seen on the list of contribution http://community.redhat.com/software/, in fact, that's quite the contrary, with people being paid full time on the job. It is a bit unfair to totally skip that part and the engineering effort that is made and sustained by the company.