And also take into consideration that RHEL6 is shipped with approx. 2.000 packages. And there are over 10.000 packages available for Fedora. Such a limited package scope is needed to be able to provide stability. And this stability is why so many loves to run RHEL/CentOS/ScientificLinux instead of many other Linux distros on their servers.
The fact that the number of packages is pretty limited in core RHEL/CentOS also makes that with additional repos such as EPEL (or RPMForge) you can have a lot of recent software. EPEL additionally guarantees that the base OS won't be updated.
Then you can always decide to backport some software for a given field, using the rest as a stable basis. As Karanbir Singh pointed out in a recent interview in DistroWatch, it can be much easier to innovate and be cutting edge in a given field if the rest stays stable, instead of doing so when the whole distribution is a moving target as in Fedora.