All of your criticisms aren't problems with the way the ride was designed, but are the fault of park management and apply to WDW as a whole. The ride is in bad condition right now. All aspects of it. The scenery, animatronics, sound, paint, lighting etc. And unless the PATF retheme is canned, it will likely remain that way for the rest of its days. But it's wrong to misdirect blame to the way the scenery is designed. Or to say the ride would be better off with less detail because you maybe wouldn't see as many problems. It reminds me of how Disney started painting previously light colored ceiling tiles black in hopes that it will hide all of the mold colonies infesting them that they refuse to clean and keep under control.
I was lucky to have experienced MK's Splash Mtn back when it first opened. It was also kept in good shape at least up until 1997 (which was the last time I rode it before 2010). Back then, the ride was receiving proper refurbs every couple years as well as overnight (or even daily) work to keep things maintained (as used to be standard practice for Disney). When I returned to WDW in 2010, the ride was in a disgusting state of disrepair and had clearly been in decline for a number of years prior. A lot of rides were suffering from similar issues, though Splash was the worst by far. And it kept getting worse and worse for the next couple years (there were even close calls of crumbling rockwork falling in guest areas that prompted netting to be installed over the queue) But it was given a thorough and very solid restoration in early 2013 that brought it back to a state that was at least recognizable to its 1992 form. It remained in decent condition for the next several years after, with more solid refurbs and even nightly work being done in between. But it has been in decline again for the past couple of years. As noted, the ride reopened from this year's refurb in as bad if not worse condition than when it closed. It is once again being run to failure, much like Disneyland during the Pressler years (arguably worse aside from thankfully no one getting killed yet due to safety issues).
WDW's Splash Mtn when maintained properly IS/WAS unquestionably the best version of the ride by far. All issues it has are caused by greed and lack of care. Corporate management have made the choice to allow the ride to rot and fail. That's an ongoing and ever growing problem that affects WDW as a whole, and it's a business philosophy that has been present for an extremely long time.