While I do agree with some of your points here (that once a cap is in place, everything else takes on a diminished role) everything will still have an impact on the competitive balance of the league, which in turn, impacts the revenues (of which, both players and owners would want maximized in "linkage" system).
For example, even if there was a cap set at 60% of revenues, you still wouldn't want to see all players get UFA status every year. The player movement every year would be tremendous, and fans would lose interest if there was nearly a complete roster turnover in their team. There also wouldn't be much motivation to develop players over a long term, as you would have little chance of retaining them. I don't think either the owners or players would want a system like that, due to the impact on revenues.
Still though, I do agree the owners seem very caught up in some of the smaller details if they are still so hung up on a cap. It's actually as if the owners are worried that some teams will find ways around the cap very easily, and they want a second set of safeguards to protect them. Either that, or they plan on offering these smaller concessions in the negotiations, but we're at a point where it makes little sense to hold strong on those items if you're planning to give them up. It's go time, and I think anything in the proposal is something that's high on their want list, and they're not interested in giving them up without a fight.