Interesting idea. However, I think that meshes cost a lot more to render than normal blocks, so it’ll probably be very difficult to do. You also have the issue that you would potentially be trying to merge blocks with different shaders involved in their display, which is also why things like gem tools do not have wooden handles.
More decorations! Definitely! It will go some way to making “ghost towns” less empty and give people more to do to keep them occupied, but I don’t think it will be the complete solution to solving empty towns (aside from more people playing). As it stands with the current player-base, they would just be prettier, better decorated empty spaces. Giving those decorations some sort of function will definitely help - and could give people a reason to visit those towns as well.
I’m starting to think that we’d need more interesting things, like (dare I say) a redstone equivalent, so people can build their own functionalities, like secret doors, moving blocks etc. This is one of the things that kept me interested in games like MC for so long.
Any sort of sellable plots, in my opinion, is too easily abused with the introduction of alts.
Additionally, even if I wasn’t a builder, I still wouldn’t want to sell off any of my plots in case additional content after 1.0 made them more valuable to me in a different play style… such as farmlands, lumber yards (grow all different types of trees that people can cut down for a fee), PVP arenas, or anything else that can make use of them in a different or interesting way.