Different parts of the country pronounce different letters and/or words differently than what we are used to here in our state. To them, the way they pronounce Wisconsin is correct according to its spelling. I suggest that the person(s) upset about the way it is pronounced start paying attention to the different speech patterns around the country. The individuals who say Wisconsin differently than we natives do are not trying to be offensive, it is what they grew up with … .Hurrah, a reasonable point!
Now, let's get a little more detailed (sorry for those who don't know about the Northern Cities Shift and such — you can read earlier posts on that). I'm still waiting for somebody out there to note that in southeast Wisconsin, [ɪ] lowering is part of a robust regional pattern. Interesting little sociolinguistic issue attached to this: Will we get a lexical exception here on the state name, while other high front lax vowels continue to lower? So, will we hear Wisconsin but whiskers showing up as wheskers? Or is this a sign of growing resistance to the Northern Cities Shift? Some people seem to be thinking that NCS is pretty fractured here anyway, so the latter seems possible.