That was a great moment - I don't know what y'all are talking about. How many schools get thrown in the longest running sitcom/scripted prime time TV series in US history? It's an honor.
And really, the only "insult" was that USC was cheaper than Harvard (or whatever Ivy League school Lisa wanted to get into) - they could have chosen pretty much any school in the country. And the fact that Lisa knew the mascot, shows that USC was at least relevant to their lives. I know this is reading deep into The Simpsons, but at one point in time it was the best/smartest satire show on TV.