Honestly, there's too much wrong with the "building" system in this game to even bother typing a big post about.
The voxel system is archaic and not that fun to use. It's too tedious for anyone but the most dedicated builders to make anything that looks good.
NQ aren't adding enough new element models to keep building interesting.
There aren't the right society management tools to allow a "civilization" of players to build things together. And even if there were, the engine can't really support a large construction project like a city or massive space station.
There hasn't been any real development progress in the past year. Without major changes, DU will continue to look like a tech project from the early 2000's and it will slowly die off.