I've asked the same thing before. Where you also told me it's a LOD thing.
In my case, I'm doing all my flying in VR. When you go into external view in VR, you end up at a predetermined zoom level. From this distance from your aircraft, the loading carts are always empty. Which takes away most of the fun with the loading carts as I'm sure you can imagine.
You mention how you took this decision to avoid affecting the FPS but how big of an FPS hit would it actually be to allow users to see the bags a bit further out? I really like to think the FPS hit can't be that big compared to many other things in the simulator both when it comes to aircraft and scenery.
If you're not willing to increase the default distance bags can be seen, is there any way you could at least add a slider where users can choose themselves from what distance the bags can be seen? That way, the users can pick between seeing bags and possibly a few FPS less or the other way around.
The way it is right now where I will never be able to see the bags on the carts in VR, that makes the whole baggage loading procedure quite useless IMO. I'd rather not see the carts at all vs seeing guys loading bags from empty carts which looks nothing but crazy.