An easy change that would significantly improve the guest experience and cost nothing would be fixing the Voices of Liberty schedule. Prior to Covid, their sets started about 15 minutes before the main show, so guests would hear them sing and then immediately go into the theater. In recent years their sets have been scheduled to start 15 minutes after the main show, so people hear them sing and then have 15-30 minutes before the next AA show. I believe this started during Covid when they were on the outdoor stage, so guests would have time to make it inside, but the schedule followed them indoors where it no longer makes sense.
It's too much time for most people to want to spend perusing the gallery inside the pavilion (which only has capacity for a handful of people anyway), but not enough time to even go get a snack and eat it before the next show. And given the linear nature of World Showcase, it's very difficult for people to go elsewhere for an hour or two and come back for a later show. So instead, most guests see either the Voices of Liberty or the American Adventure, but not both. Realigning the show times (as was done for decades) would cost them nothing, yet would improve the guest experience.
I also think VOL used to perform later in the day, giving guests time to make their way to the back of WS after spending the morning in FW. Yes, WS now has more people in it early in the day with the addition of Ratatouille and the Skyliner, but the vast majority of visitors still don't make it to the back of the park until mid- to late-afternoon. With VOL's last performance at 3:45, they're no longer something most guests can easily discover, and instead must be sought out.
Speaking of scheduling, AA is only a couple minutes longer than HOP, yet HOP operates 'continuous' shows and AA has scheduled times every 45-60 minutes throughout the day. On the one hand it's nice to have a scheduled time to aim for since the location is far from much of the park. But on the other hand there are very long gaps between shows (particularly later in the day, when most guests are actually in World Showcase), so if you miss one it's probably not worth waiting for the next. I'm not sure what the best solution is, but the current approach isn't great. Like so many things in WDW, the bones of a good experience are there, but the way they're operated makes it very challenging to optimize your time (see also: Impressions de France schedule).