I've thought about this for some time. I find IT Crowd really funny, but I can't connect with TBBT. My thought is that in the IT Crowd we are laughing with the Geeks, in TBBT we are laughing at them. Certainly IT Crowd has stereotypes and exaggerations (comedy would almost be impossible without exaggerations, by the way), but it develops more empathy toward its characters and allows us a way into their experiences much more than TBBT. Take Jen, for instance. Even though she is a stereotype (woman who doesn't understand computers but somehow ends up in charge of IT), she's portrayed as a real person who wants to do a good job and recognizes her shortcomings but just wants to be successful (and really the joke is on the higher level management who hired her without knowing anything about IT or computers, either!).