I think the public perception of the conference has continued to decline. I think the actual decline is overstated. OSU outside of this year when their QB goes down has been highly ranked like they always are. MSU has been a legitimate second power most of the past 5 years. Wisky and Iowa have been highly rated as well at different times.
OSU may have been in the national championship if it weren't for the sanctions at the time. This year is a lot of bad timing, but I hardly think the conference is falling apart. The only team that's been in serious decline the last decade is Michigan. Michigan is a big name program, for sure, but teams have stepped up to fill that void pretty well (MSU/Wisky).
This is like the reverse Notre Dame syndrome. People see the ND name and assume it's a good team, even though they haven't actually been that good for the last 20 years. People see Michigan bad in the B1G, and they assume the whole B1G is bad. This then becomes a self-fulfilling belief. Because if the conference is perceived to be bad, they don't get highly rated and then don't get the bumps up the charts from beating other teams in conference. This gets worse and worse because it means any loss is a terrible loss and any win is a pointless win. Again, that's not to say this isn't an actual down year, but down from the heights of having a team at the top of the ranking all year is not the same as down to a division 2 level, which is how a lot of people talk.