Chris,

The problem with CUs is that most people don't have time to test. They won't waste time testing them, even for small issues. These updates are not tested as well as SPs, and most of the time when I've been in companies we would plan on SPs to ensure support, and fix minor things, but we wouldn't necessarily do that for CUs. Also, while you might find a fix in a CU, you need to backtrack through all previous CUs to see what else might be affected. They are cumulative of previous CUs.

If there are critical issues, people do apply CUs, but the majority of people I've spoken to don't want to bother with them.