James Gasik
We don't talk about Pun-Pun
Sure, but if the ability is that important that you need to take a Feat or a class dip to get it, maybe it's too good?The Rogue gets expertise in four skills over its career. So does the bard. The ranger gets three. The wizard gets it in one Intelligence skill. Anyone can get it in one skill of choice at fourth level with Skill Expert. Expertise is painfully easy to get. Much like weapon mastery, it's never more than one feat or one level dip away.
Plus the main problem is that Expertise is limited, there's always going to be skills it's necessary for and ones that are pretty niche. I don't see people taking Expertise in Medicine, but Perception or Investigation? Absolutely.
If I told my group to make a DC 25 History check, I'm sure I'd get some hearty laughs in response, as none of their classes are Int based to begin with.