I guess there might be a couple of reasons. I don’t know for sure. Perhaps it’s a nod to the modding community. This engine is so, so old that it’s (comparatively) easy to do graphical mods with it, and the modding tools are pretty readily available, even without a Creation Kit or whatever.
But it may also be that something that you mentioned, like the interaction between the graphical “world” and the complex db and commands underneath could be a daunting problem to try to solve, and one that Bethesda seems uneager to try to tackle.