In terms of chances at making the post-season, MLB is more competitive than the other leagues (including the NFL). Same with the championship games. There are just different reasons for the lack of parity.
In leagues with salary caps, small and mid market teams can succeed. In MLB, they can't. Jeff Passan would make the same argument I'd make a couple years ago about how teams can make the playoffs so everything is okay.
MLB teams cannot advance in the playoffs based on payrolls. No team in the past decade has made the World Series in a full season while in the bottom half of payroll. The smaller market, smaller payroll teams are honestly just cannon fodder for the real competitors.
I want to see much closer to full rev share, a floor system of some sort. If it's not a hard floor, I want it to have teeth. Like every $10MM under the floor, lose your top pick. Go $100MM under the floor lose all your picks for the first 10 rounds. I want to see a hard cap or at least a prospect forfeiture tax. i.e. The Dodgers can go in at $300MM, but for every $10MM over the tax, say starting at $220MM, they lose their top prospect. That means they lose their top 8 prospects who are allowed to be selected as competitive balance picks or something like that. The ceiling has to have real teeth and long term consequences.
I like the "tank/rebuild" strategy overall. It sucks for a couple years, but I think it's a good alternate strategy to just "spend more!" In other salary cap leagues, there's one strategy. Get lucky in the first round of the draft.