An opportunity for the defense to score a run if the bases are loaded
I wanted to throw in one fun, wacky rule idea to this list, and credit to my dad for floating this idea around for years now. I think would add a really fun wrinkle to an already stressful situation for teams in the middle of games.
For this rule, any time the bases become loaded with no outs, the defense is now also in a position to score. How you might ask? Well, if the bases are loaded and there are no outs, the defense is able to score a run if they do not allow the opposing team to drive in a run. Think about how much pressure that would add to the team at the plate, knowing that not only would they miss out on adding some runs, but they'd actually gift the opposing team a run if they did not score.
When you think about it, this actually could create better at-bats from teams with the bases loaded as well. Until they put at least one run on the board, the hitter is going to need to do everything they can to put the ball in play and try and get a run home, rather than just swinging for the fences and potentially coming up with nothing.
Out of all the rules changes, this is the most "out there" idea of them all, and one I'm least married to, but it feels like a really interesting way to add some intensity to a big moment in games and to reward teams for getting out of a difficult situation. It is such a relief for a team when they are able to hold the opposing team to zero runs when the bases are loaded, and now they'll have another reason to celebrate as well.
Also, it would incentivize teams to move away from the "bend but don't break" mentality that the bases loaded can sometimes bring, getting the pitcher on the mound to be more aggressive with their pitches to allow no runs, rather than being "okay" with a run-scoring.