Hi Shrst. I can understand your frustration if you are trying to do what you’ve said you are doing - taking an existing model from an external 3D app and converting it to Unreal.
If you want quick results, you could set all of your geometry to movable inside Unreal and try to work with the lighting to compensate for the lack of light maps. You could place lights, play with the post process settings and change the overall feel of the scene to make it look appealing.
Unfortunately, to get the results you are probably after using light maps means that you are indeed going to have to spend the time to create them. It can be, as you say, a long and tedious process, but keep in mind that Unreal is a game Engine and as such it requires the appropriate steps to make things work. You can’t pretend to have an uber quality product with the work you’ve already put in your 3d app and run it smoothly without some extra work.
My advise for the next time would be to start modelling with your end goal in mind, so you can start creating and modelling in a way which will be helpful for your final application (Unreal in this case).
On a side note, you might be interested in a tool that Epic Games has just announced: https://evermotion.org/articles/show/10771/datasmith-import-your-scenes-to-unreal-engine
Cheers!