Sounds great. Also sounds like a ton of work, at least to do it right. Like a year i bet lol.
Somewhere on old forum was an idea to add a Build-Boy upgrade to Pip-Boy, but it would basically be a whole additional GUI screen where you build anything you want in "dream mode", then burn it to a holotape when done. Next, you hire a construction worker (just like now with DYI bases, but you use the tape somehow in the transaction) and place the site and bring materials there. When it is done, you get a custom base/house/farm/whatever.
The reason i don't see it happening, though it would be so cool, is time. Designing a new interface with its own GUI is one thing, but a function that allows us to place individual map tiles, even tile_blocks in certain ways that fit, is a gigantic feat of coding, so it would take a year i bet.
It would be a lot easier for players to dive into the Mapper tool, design some quality bases that work, and submit them for review and approval by the dev team.
As for gun turrets, yes people have asked for that too. Think first, why? As it is now, factions cannot attack each other's bases so defending bases is not necessary much. Maybe if we open up bases to be seen/attacked faction-vs-faction, that would be a start. Let's say...a base still does not show up for non-member/friends until it is a faction that has successfully done Town Control. Once you do TC, your faction base can be attacked for like a week. That would make gun turrets and otherwise defending bases a new thing.