Mind Your Language might not have been smart comedy, but it was good comedy with the misunderstandings stemming from a valid observation of differing cultures. The idea was not dissimilar from other sitcoms of this time such as Robin's Nest: a small matter, concealed, becomes a major matter after 15 minutes. Throw in the xenophobia of Britain after it joined the EEC and what we had was a very fine comedy about the country's relationship with her former colonies and the new Johnny Foreigners across the channel.
If anything, the students got the last laugh if it had not been the narrow-mindedness of characters such as stiff-upper-lip principal Miss Courtenay, or teacher Jeremy Brown finding himself out of his depth, then the joke wouldn't be on them.
It's a pity the political correctness brigade will probably prevent this show from being rerun. As a "minority", I never found the portrayal of my race offensive on this show when it aired in New Zealand. To the PC thugs, I say this: we minorities are OK without your defending us. The real insult is that you don't believe we are up to it.