Huge baseball fan here. Surprisingly I agree with almost all of these recommendations, except for the first one and the last one. No, do NOT shorten the season to 140 games (from 162.) No, DO NOT add two more teams. The talent pool is diluted enough already. I would be OK with eliminating 2 teams (so long as it's not 2 of my favorites, of course.)
The problem with baseball is that the games take too long and the pace of play is too slow. These two things are interrelated but they are not the same thing. Many items on the list address these two problems. Just about everything else on the list that doesn't address this is trivial. Too many uniforms? So what? Minor league players don't get paid enough? Too bad. Limiting the September callups is a solution looking for a problem. Ballpark noise pollution is a problem that crosses every major sport. I say it's the worst in the NFL, MLB is next, then NBA, and then NHL.
Too many mound visits and batters slowing down games should have been near the top of the list. There is no reason for a batter to step out of the batters box AFTER EVERY PITCH and adjust the wrist straps on his batting gloves, especially if he didn't swing! Too many mound visits has been addressed by a rule change instituted this year that limits them to 6 visits per 9 inning game.
Curious, but there was no mention of a pitch clock. This is being used in the minor leagues right now and gives the pitcher 20 seconds between pitches. If the pitcher does not throw the next pitch within 20 seconds of the previous pitch (on a pitch that was not put in play), the umpire shall call a ball and if the batter is not in the batters box ready to hit within 20 seconds the umpire calls a strike.
The other thing about baseball that makes it nearly unwatchable for me is the terrible lack of fundamental defensive play. I am not exaggerating--I can turn on any random baseball game, any, and within 5 minutes I will see a defensive miscue or a lapse in judgment. I'm not necessarily talking about an error, I'm talking about things like outfielders not hitting the cutoff man (or throwing to the wrong base), infielders backpedaling on a fly ball trying to catch it instead of allowing the outfielder to run in and catch it (much easier for the OF to see the ball running towards it than the IF running backwards), outfielders not calling for fly balls and having easily caught balls drop for hits between 2 OFers (these are not errors because no one touched the ball), and on and on I could go. Being a former coach, it's very difficult to watch this sort of mayhem, especially at the major league level. My kids are sick of me complaining about it, but I am compelled to point it out to them.