These would be the two most difficult things to import. Object placement being difficult considering there’d be no objects for it to import, and terrain being difficult since it’s a different engine. (If by “terrain shape” you just mean the heightmap, then that shouldn’t be difficult at all and is likely already feasible in a manner similar to Unturned (3.x).)
Unfortunately, even if it was possible to port those two things, it will not remedy this concern in any way. Building terrain and placing objects are the easiest parts, hands-down.
Bad/lazy content is not beloved/good. That’s not new content. That’s people being too lazy to make functional custom content that people would actually want to play with.
Personally, I’m just fine with waiting a day or two after the beta launches for some “actually quality” community-made content. People have started on making their own custom content right now. When Nelson starts releasing assets for people to work with too, it’ll be even easier for people to get started before the game is actually publicly available.
Good mods being available at the start of when an easily moddable game is released is good. From my understanding, people find the current state of the Workshop to be quite low-quality (with a few exceptions), and don’t want a repeat of that in Unturned II. Rushed out mods don’t help this, imo.