Settlers A.I. leaves a lot to be desired. I came to my Red Rocket base which had at the time 15 settlers in it. I built a generator room by the Gas pump out the front (the one you can't scrap). It was 4am so you'd think that most people would be asleep. Not so, 13 of my 15 settlers were standing around crammed into my generator room, completely inexplicable.
I don't like the fact that I am reconstituting steel from tin cans and other miscellaneous items, yet I can't make one that doesn't look like S**T. And I can't make a roof without holes in, my character is not a D**K, if he makes a roof it shouldn't have holes. I really hate how most of the wall sections you can use look awful and there is no variation to them (the texture is always identical) giving some of my creations a very PS2 look to them.
I have a very hard time placing shops indoors, unless it's a pre-existing buildings with a high ceiling. I have not yet worked out a way to place a wall section on top of another for a higher ceiling, If you place another floor then a wall then remove the floor in between there is a gap. I want the option for higher ceilings.
I don't like how sometimes an item is inexplicably un-placeable in a certain location, I was building a 'shopping district' in one of my Sunshine Co-op, I put down a general store, tried to put down a food shop next to it, won't go there, Weapon shop will, Clothes and Armour shop, no problem, they can all be placed next to each other apart from the bar, so I had to put it separate to the rest, silly problems.
Support pillars so elevated builds or big rooms don't look silly.
You should be able to put down a pre-fab and edit it rather than only being able to delete the whole thing.
Definitely need to be able to build with bricks/cinderblocks, even if it's just in sections like the existing walls, it's illogical that you cannot build with bricks.
More signs and wall decorations, there are so many obvious ones that they didn't think of.
It would be cool to be able to have a list of your settlers and see what job they are doing and whether they are assigned to a bed etc. Also the ability to re-name settlers would be awesome.
You should be able to lay pipes down and plumb in sinks, toilets, baths and showers etc.
I don't like the fact that you cannot clean up, If I were fixing up a post apocalypse dwelling, I would at least sweep away all the rubble and debris from the floor, this is a feature I would like, my settlers deserve a clean floor. Some settlements I don't use because they are too dirty looking.
A VAULT SETTLEMENT PLEASE!!!!!!!! A no-brainer and I was shocked they didn't think of it, or if they did they should have included it.
Bethesda have created a wonderful feature, one that people will be modding and expanding upon for years, and I can only imagine what they could turn the feature into in the next Elder Scrolls. And my criticisms are merely opportunities for improvement, there are lots of things that are already perfect about the system! I have faith in Beth and modders alike.