G'day. Just thought I'd share some Ideas I've collected from my own experience and other players:
Watchtower platforms should not have any holes in them if there are no stairs built underneath.
This would allow for much more interesting structures to be built.
Lowest level of the watchtower should have an option to build a floor (preferrably without the need to add the four pillars to it - maybe just 2 for X-shaped support underneath).
This would help with uneven ground and prevent access from underneath the tower as well as allowing more interesting structures
Using pliers on the inside of a structure should disable/enable it's visibility in the inventory interface
(would also help with the camo nets being accessible from the outside perimeter) : call it a "Finish Structure" and "Edit Structure" activity when approaching with pliers or something.
No more messy inventory near fences!
Bring back old fence alignment as described in https://feedback.bistudio.com/T144079 (seriously, please bring this back)
Crazy awesome structures could be built on servers where placement is allowed everywhere.
Add half / third-width fences and gates.
These would help immensely with difficult base layouts and, if the next suggestion is impossible, help with closing off vanilla structures in a more sensible manner.
Add option to convert a vanilla door into something a combination / code lock can be attached to. Maybe using a screwdriver on a door to convert locks?
Doors can already be locked and unlocked using a lockpick - so why not take it to the next level?