Heh, I'm probably the opposite. I like the settlement building capability in the engine, but don't feel that Bethesda's done a lot with it in any of their games.

In Fallout 4 you can make pretty settlements, but there's a very minimal degree to which layout interacts with the game. Putting some walls up around expensive stuff and making enemies need to go past turrets or guard posts helps a bit, but it's basically just SimArchitect. Lay out stuff how you want for fun. That's not bad as such, but I'd like to have more interaction with the game world. Also, using settlements without the Local Leader ability to let settlements trade goods was a pain, which was one of the few useful things in the Charisma tree. There is one quest where one does lay out defenses for a significant fight, bur that's about it.

The Sim Settlements mod introduces settlements that build themselves, which gives you elaborate, evolving things without having to manually do all the work of building them (and can take advantage of newer hardware with larger settlements). That's nice, but it really just provides an opportunity to rebuild nice-looking stuff in without the scrap-hauling and placement drudge work. The mod adds a (fairly extensive) questline, but the actual layout of the cities again doesn't matter much. Avoids the need for Local Leader as a quality-of-life perk, so provides more character build flexibility.

Fallout 76 has some game-important roles to a player's CAMP, but it's basically providing convenient access to workshops and a player vendor. Defensive layout does matter somewhat-more, as attacks when a player isn't present are actually simulated in the game world. You can take and hold certain map locations, sorta a tower defense mode, but there's minimal reward in the game for it. The point is still mostly being Sim Architect for player CAMPs, except now you can show your creations to other players. CAMPs are much smaller than Fallout 4 settlements. You can also have Shelters, which are little areas to free-build off the main world. Like CAMPs, but with a few restrictions, like the inability to have resource-producing items (and automated resource production is very limited, rarely worthwhile). Some players have done neat things that add to the game, but again, just doesn't feel like there's much "game" to it. Fallout 76 has some hard limits on ability to store things in a CAMP -- inventory limitations are a core part of the game.

Starfield has multi-base spanning automated production, and automated production matters, more like a very limited Factorio. However, you can pretty much play the game and ignore that aspect, as the main purpose of getting resources is...building more bases. IIRC, bases don't get attacked when you're away, and defenses aren't an issue. I guess that's nice for people who don't like base-building, but it felt like kind of a pointless loop to me. Not like, oh, Egosoft's X series, where you build out a space empire to get more stuff that unlocks more things. You can buy player homes, but they never felt as useful to me as Home Plate in Fallout 4, as I just usually wasn't passing by the player homes, and the ships are generally more available. I think that those are more aimed at people who want to do interior decoration. Starfield does let you modify ship interiors, but there just isn't a lot of gameplay point to it, though it's probably where I spent the most time. There just isn't that much that happens in your ship.

None of those are bad things, but the base-building aspects just feel kind of decoupled from the game, like a kind of bolted on architectural program. If you want to create your dream space home, I guess that that's fine, but I was kind of hoping for something that heads more in the Sim City or Caesar direction, where there's real gameplay associated with the settlement you build. If one wanted to do just aesthetics, maybe in Fallout 76, let players build new stuff in contests and then whoever builds the neatest gets some award and the structure gets incorporated into the base game, something like that.