I run stock Android, unlocked and rooted, but I can see the appeal of CyanogenMod. Notably, it has some nice / nerdy controls that let you crank back on permissions given to apps. Yes you require access to my contacts list, but you're not getting them.

So far as I can tell, the bulk of people installing third-party distributions are either interested primarily in getting away from vendor crapware or they're just interested in some of the crazy skins and such that the third-party universe offers.