Bounding box editing and import/export
Well, bounding box editing capabilities would be very good to have. Current calculation on export isn't perfect and leads to problems with camera on vehicles, but also cause a need of RWAnalyze edits when doing something like bagboxa trailers (bagboxa trailers treat rear edge of bounding box as a hookup for another trailer)
Here you can see that box is too high and too far back, which causes camera issues.
Here is the problem with bagboxa special features hookup, top is just exported ussing DragonFF and bottom (this is how it supposed to look like) is edited in via other means

Another thing is editing map object bounding box which actually decides when object is loaded/unloaded from view, when editing something like wires for example it's hard to have appropriate bounding box and often i had to add some poly just to extend that, then recalculate it with CollEditor and remove that unwanted col poly after that.
Does Apply All Transform not help?