I'm also not convinced that ladder-climbing, whether one wants it or not, is a fundamental engine limitation. It might not be in the game, but that doesn't imply that it's an engine limitation.

googles

This guy modded climbable ladders into Fallout 4, which seems like a pretty good argument that it's not an engine limitation.

https://www.nexusmods.com/fallout4/mods/62738

And not that I object per se to ladders, but when was the last time you climbed a ladder in real life? I haven't in quite some years. I mean, sure, it's one more interaction, and IIRC there are some fire escapes that had ladders somewhere in Fallout 4 in Boston. But you could make the same argument about interacting with all kinds of things, and it just seems odd for so many people here to mention specifically climbing ladders. I mean, you could fall and catch yourself, drive vehicles, rappel on a rope, skateboard, ice skate, grapple with enemies, zipline, sail a sailing boat, or God knows, any number of other player-object interaction functionality things that might be added. I suppose that any of them could theoretically add gameplay, but I don't see why the criticality of ladders.