They probably don't, actually.. but judging by various utterances in that vein they've made, I think that to most of CCP the server and protocol are holy writ they're not allowed to touch. That does limit things rather a bit.
It's more that the oldest server and game code has little to no documentation, so messing with it is very risky. Unless the person who wrote a particular part of code still works for CCP (and remembers how he wrote it), with no documentation there's apparently no way to know what each line does. So for any change that involves said risky code, CCP needs to dedicate a team to interpret the old code and figure out how it works or rewrite it from scratch with a new system.
This is the reason Crimewatch is being rebuilt from the ground up instead of edited, and is the reason CONCORD billboards went unfixed for years.