This could all be fixed if they finally abandoned the PPV model and broadcast their numbered events with commercials. Then streaming wouldn't really matter because the advertisers would still reach those eyeballs and be willing to pay to do so.
The average UFC main card lasts 180-200 minutes but contains only 50-55 minutes of fight time. That leaves plenty of time for commercials.
For regular season NFL games with national audiences, advertisers pay an average of $811,700 for a 30-second commercial spot.
If ESPN charged even half of that for a commerical on UFC numbered cards (instead of making them PPVs), they could make $60.9 million ($405,850 per commercial * 2 commercials per minute * 75 minutes of commercials during 180-200 minutes of air time).
That is the equivalent of 812,000 PPV buys at $74.99 a pop.
Most UFC PPV cards fall short of 400,000 buys. ESPN pays the UFC the equivalent of 500,000 buys in the current deal. But they would earn much more if they took it off PPV and just aired it with commercials like other popular sporting events.
The PPV model made sense when the UFC struggled to attract mainstream advertisers. They don't have that problem anymore.
It would make much more sense to broadcast the cards with commercials instead of behind paywalls and PPV. Not only would it be more lucrative, it would also more readily grow viewership by making the product more accessible and more likely to reach to new fans.