It goes deeper than athletic departments and like I said is stronger among Big Ten alumni than non alumni sports fans only. The holier than thou attitude is for your new conference, which you are now in. You should share it and be proud of it. Touting the greatness of the Big Ten culture should not be offensive to you. I'm trying to explain it. There is still hatred on the field, so if your only experience with the Big Ten is 8 Saturdays per year, you might not notice.
You talk a lot but you don't say anything, and you talk in circles. You start off wringing your hands that we don't care about one team, then morph into some nonsensical point about the alumnae of various Big Ten schools feeling camaraderie for each other. Which do you want to talk about?
No circles at all. My point is, if a Big Ten school left the conference after 100 years, the Big Ten reaction would be different than the attitude I've read here, which quite frankly surprised me. "Meh" would not be it. It would be a reaction of regret that things didn't work out, even if it's for the best. I've tried to explain why that is, due to the Big Ten's history and culture. I hope in time Nebraska comes to share that. It has helped the Big Ten survive as long as it has.
So basically your point is based on hypotheticals about a conference you have apparently zero understanding of the dynamics of and a move you've never been around to experience as a fan of a team leaving a conference.
The old big 8 died 15 years ago, so you can give up the 100 years of history arguments right now. That history was thrown out the window when Texas was added and started dictating how the league would be run before they even joined... We've had 15 years to mourn the loss of OU/Nebraska rivalry and I think plenty of husker fans are sympathetic to the bad situation the old big 8 teams are in now, particularly the northern teams. We just left it, we are thankful to be out of there. You're trying to romanticize the history between the programs as if the big 8/12 was the equivalent of the Big Ten. It wasn't and it never will be.
ISU is a perennial doormat, once in awhile they have a good team and/or beat someone surprising, or caught a fluke game like 8 turnovers, but by and large it was a game that for 50 years was something when you saw the schedule you just chalked up as a W and looked at next weeks opponent.