CentOS and RHEL are positioned as enterprise OSs, and in the vast majority of cases they are installed on headless servers that have no need of gui apps.
Not to be argumentative, and we are wandering OT here, but can you quantify "vast majority"? The default install will still give you a GUI.
I grew up as a command-line guy (actually back to punch cards, but that's way OT) and do much server management management that way remotely, but the GUI tools have their uses too.
We have a number of CentOS systems at work, desktops/workstations and laptops, as well as compute, file, and web servers.
None of my servers are actually headless (not counting those on KVM switches as headless) and most have the GUI installed, if not active.
At home my wife and I both use CentOS for daily use at home, as well has having it on a couple of laptops. The kids have even been known to use it for web browsing, music, myspace, etc.
There are a lot of forum and ML posts that indicate people are using CentOS for daily desktop use and multimedia. Relatively few posts explicitly address headless systems.
If I were in charge of Chrome development I wouldn't waste time on a market segment as small as CentOS either.
I might not either, but that might depend on how easy it was to do. If the older package versions made it difficult, admittedly probably would not put in a great effort.