A tool to select numerous entities at once for removal would be a great help.

I think a bunch of other thoughts have been expressed before, but for what it’s worth, my wishes are:

A wider variety of characters, inc: Snipers, heavy machine guns, suppressed weapons, average folk who can be assigned various basic behaviours from a selection of scripts. Also other creatures such as: Dogs, cows, sheep, demons, dragons, trolls, Yorkshire men etc..

I’d like to see my legs and lower torso, I’ve seen this has been done; can it be introduced fully rather than a customised addition?

More vehicles and vehicles that move via assigned paths/way points.

Water falls and rivers would be cool, as would the ability to increase the appearance of suspended solids in the water (make it murky).

More options on surfaces would be nice.

Rain would be fantastic

More character interaction options. eg. Using a laptop to enter something, manning a fixed gun, driving a vehicle, lighting candles. Switching light switches, kicking down doors, taking pictures, pushing objects, climbing ladders.
Better ability to import 3rd party characters, more versatility to allow alternative shaped creatures/characters.

No idea if some of that is possible, but from my perspective (someone who is completely ignorant of programming, but pretty skilled at a variety of commercial terrain and image software), they would open up the potential to provide a much richer creative experience, without actually being too creative.