Simulcast reduces the value of the rights due to their non-exclusivity splitting the viewer market. This is pretty inescapable, I'm not sure on what grounds you'd think to argue it? They may have overlap in part-ownership, but neither broadcast partner is going to simply consent to giving charity like that.They are both owned by the same person. Simulcast doesn't reduce the value of rights. It would reduce value of channel 9s games but up value for fox sports otherwise fox wouldn't bother.
Also streams are starting to hurt. You can get all games live in the UK or in France so people stream them.
Having delayed sport decreases ratings.
Delayed sport may decrease ratings, but not being forced to broadcast live gives the network flexibility to program as it will.
Anything that gives the networks exclusivity and/or flexibility increase the value of the broadcast deal. Things that take away those attributes make the product less useful/appealing for a broadcast partner, thus decreasing the value.
The AFL has been putting up replays online post-match for a while now, and I believe have a live-streaming system in place now, although I don't know many of the specifics because I haven't ever needed to make use of it.