Are we too hard on Texas?
I think there are several reasons why Texas gets as much flak as it does. For one thing, most people who have never been to Texas (as I have) don't know much about it. There is a lot more to it than the stereotypes -- see Ranch Chimp's post. But stereotypes are easy to latch onto in certain situations -- and yes, I've done it too.
Also, Texans seem to be pretty good-natured about the ribbing -- they themselves make jokes about Texas. People may feel more comfortable making fun of Texas than other states, since Texans seem less quick to be offended. In politically-charged times, this can take on a harsher edge, especially since Texas is the biggest consistently-red state and thus gets taken as emblematic of them. Think, though -- how many states have such a distinct identity that there even are stereotypes of them? Regions, yes, but individual states? There are stereotypes of California (gays, Hollywood), Utah (Mormons), maybe Florida and Louisiana, not many others.
Texas is also where Bush came from, and unfortunately he tended to reinforce the worst of the stereotypes.
Finally, there's no denying there's been a real outbreak of high- profile gooberism in Texas lately. There's the Repent Amarillo thuggery. There's the dumbing-down of school textbooks. There's Louie Gohmert and his demon invasion. There's the governor making noises about secession, which is beyond a joke -- that's treason talk. (And I'd say the same to all of those who sometimes remark that they wish Texas would secede -- it's not funny, and it dishonors all those who died in the Civil War fighting to hold this country together.)
But again, while this is all true, it's not the whole truth. A point Ranch Chimp has made is that Texas has a potential Democratic majority -- its black and Hispanic populations are huge, for one thing, but tend not to turn out in great numbers for elections. If all qualified citizens voted, Texas could well become a blue state.