Your missing my point...The 'casual fan' is such an overstated myth. The 'casual fan' happening to find a game does nothing for driving revenue and networks don't even typically look at raw numbers of viewers, it's all about the younger demo and that demo doesn't have cable anymore.
Two guys named Chris nailed it on IowaEveryWhere this AM. You should take a listen to the conversation if you are interested in the topic. Streaming is not going anywhere and will be the future. But currently it is not as good as linear options for exposure.
There are ways to improve the quality and make it better. Look at the NCG with multiple camera angles during the game - including an all 22 view of the field, or the fact that you don't need to cut away for another game after, you can show the court before, after the event, do post game player interviews, stream coaches interviews, get expert analysis after the game, etc. right from the same stream for those interested. The point is there are built in advantages that are not fully exploited today and many built in negatives that are not covered up well.
Bottom line, the CURRENT production quality of ESPN+ is not great, definitely JV production quality. It's also more difficult for sports fans (not ISU/tx fans) to happen to find the game and tune in. This matters. You are 100% wrong on your casual fan comment. Casual fans are literally the reason tosu, mich, nd, bama, etc. have such significant media value. The reality is, casual fans tune in to watch brands and to watch top games.
I am not saying that ISU MBB is going to have the appeal of OSU FB. But a top 15 match up is going to bring in casuals. It happens all the time. By having big games (ISU v. Kan, ISU v. Tex) on espn+ it impacts the reach of your conference. It is good for ESPN (they drive interest in ESPN+). It is not great for the B12.
B12 future value is dependent on continuing to build their brand value. Long term, streaming is a key piece of every sports media deal. Short term, you can impact brand value if you do not maintain exposure of you top conference content.