1) Current ticket prices reflect generally what the market will bear. and StubHub and other secondary marketplaces iron out much of any remaining arbitrage there is to be had. If the owners unilaterally lower ticket prices, scalpers will swoop in to an even greater degree and snap up all available tickets and wait then for their market-correct price to be eventually met. Either that, or fans who tell the world "give me cheaper tickets" will instead sell their windfall in the same way to other fans who are willing to pay more than you or I.
2) MLB already has a problem of luring good athletes who may also be NFL or NBA candidates. If the salary pool is decreased, that problem becomes only worse - imagine the next Joe Mauer throwing touchdowns for Florida State.
It's a fantasy/dream that the "greedy" athletes will somehow be punished into toeing some arbitrary line. I'm no free-market woofer, but anyone proposing to go against the market needs to have a plan for how to deal with the discontinuities their plan will raise. The money is there to be had, and if the athletes don't get it then someone else does, but not you or me.