I agree it's immersion-breaking to see your party jumping around like superheroes. It also forces some non-intuitive choices, like choosing +1 to strength as the first stat upgrade for my Rogue, just to increase his jumping distance to get behind someone. Strength isn't supposed to be that critical a stat for a Rogue.
Unfortunately, it looks to me like the jumping distance is very tightly integrated with the scenery design. Not just combat encounter areas, but available travel paths outside of combat. Some areas you can reach now would be off-limits with a shorter jump, and reducing the AI's jump could screw up their programming. Larian may not be able to just reduce the jumping distance without completely re-drawing the scenery areas, so I suspect this is something we're just going to have to get used to.
I believe that they could fix jump within the existing framework without too much work.
1. Remove jumping up onto raised terrain: They already have climbing rock faces implemented, a climbing spot for areas that were jumpable could be added to those sections that are basically jumpable stairs at the moment, but they could leave the ability to jump down off of high terrain and risk fall damage.
2. In combat, remove jump entirely: replace with a disengage button per 5E rules
3. Leave horizontal jumping in the game outside of combat: this way rivers and bridge gaps etc, can be crossed, and doing so would alleviate the need to drastically alter terrain.
