I get you, diving lots do seem a bit out of place in non tropical worlds. After a whole lot of time yesterday I was able to get one to work in my world, but I have made a small one, not a 64 x 64 lot like most in Isle Paradiso. Maybe for your worlds you could do the same, make several smaller dive sites. I actually have a friend who is a fisherman and goes diving and he did say that even non tropical oceans have amazing and unique underwater landscapes and they can be quite localized, so its not unusual to have a really lush and packed area randomly among not so interesting terrain.
Check out some of Rflong7's worlds if you want to do some more research too. They are hugely popular, as I said my favorite is Ridgeview in Summer, that will give you an idea of what I meant in my wishlist. You will see the shore lines are lovely open sloping beaches but not really suited to houseboat ports, other than that the layout is nice with open space but a few little districts and laneways, nice size too. I also love the aesthetic, lush and well kinda of generic so it suits most stories. Not saying you are building a world depending on what I want, just saying Rflong7 has an example of almost everything on my wishlist.
Also the more I think about it the more I do like the idea of having some pre-made families and houses, and like you said if someone doesn't like them they can just remove them. You could also upload 2 versions of your town when it is made, one with the finished lots and households and another with just blank lots or only some finished lots, having a town with only the necessary community lots finished and everything else empty is also a popular way to upload worlds.
