YES! I absolutely want to be able to go out and edit the neighborhoods. I'm glad they added color to them because I absolutely despised the basegame gray neighborhood. The neighborhoods are so small, it would be nice to be able to create custom neighborhoods too. We could use existing ones as templates, but creating completely new ones would be nice too. I would love to create more alien world neighborhoods for Sims to visit & be able to go there via spaceship or via teleporter devices. I would love to add some of the stuff from Sixam to other neighborhoods-- have a funky alien area inside a giant dome or something.
In addition to adding more trees and decor, adding more lots & adjusting the size, I'd love to be able to add spawners for crystals, metals, scrap piles, etc (I only found scrap piles twice and have no idea if they are regular things or where to normally find them). A scrapyard lot would be cool.
I would also love to be able to access & edit the various places the sims work at when the sims are not working or when I don't have a specific sim selected. Right now I can't even find the workplaces when my Sim is not there. I want to edit some of the venues because they are too small or don't have enough fun stuff. My sim got invited to a party by his coworkers & the place was awful.