Looking back at the last few years, most of the Week 0 lineup is generally made up of games that wouldn't be televised in a normal week, and even the stinkers are often getting prime cable slots (ESPN, FS1). Plus the marquee Week 0 games seem to consistently draw much better than similar Week 1 matchups.
Considering how many Week 0 TV slots are going to random G5/FCS matchups or just going unfilled entirely, I do think there's a LOT of ratings being left on the table here. The B12 would dilute the market a bit by adding 8 games to Week 0, but they'd basically be a lock to grab multiple OTA timeslots with their best games and the rest would be on prime cable spots. Whether that's monetarily worth it or not would be a discussion for the B12 and their media partners, but I can definitely see the upside.