Speed. When blocking in a level, I don’t want to deal with the whole export/import pipeline whenever I want to run around and check scale. Blueprint construction scripts are a pain to work with compared to the ease of a BSP boolean workflow for level design, there’s no comparison. It’s not only slower using construction scripts, but I then need to get a programmer involved and can’t just let an artist handle it alone.
I mean, it’s certainly possible, but if it’s really going to be an insurmountable hurdle, could just make a Maya plugin that links Maya to Unreal and replicates marked meshes as they’re edited in realtime. Since the CryENGINE has already been brought up with the Designer Tools, an obvious comparison would be LiveCreate (https://youtu.be/ZqNHJ-ekMR4?t=28). I could see it being useful for both level designers and animators in this regard, being able to preview models and animations with the full set of Maya’s tools, basically using Unreal as a viewport.