Yes, more complex shapes, or those with odd angles, are more needed. The rightmost item, for instance. Most of the others seem to me to be easily reproducible in the mission editor just using brushes. Objects like dishes, flora, odd-shaped vehicles, fancy street- and building-lights, bent or otherwise deformed versions of simpler objects, etc. You may want to
Though take what I say with a grain of salt. I'm not a project member; if you want to get more specifics, pay attention to the people in the know (like BTAxis, above). I would suggest you have a look at the editor, as well, as you could also contribute brush prefabs of some of the simpler objects you would like to model, which could be used and altered by mappers quicker. It may also help you get a better feel for what sort of models are needed.
