I think Nexuiz needs to come with tree models. You cannot really create trees that look good in the editor so you must use a model. I have seen tree models in other extra maps but I think it would be good if trees came with Nexuiz because it is unknown how those other trees may be used by license.
If Nexuiz bundled high quality trees of various types and other plant life then this would increase the gamut of map types that could be created using nexuiz media without worrying about ambiguous copyrights on community created maps and models. We could have "lush" maps as other games do. Right now such maps are few and far between.
Func_door_rotating is needed as an engine improvement so we can have normal doors in some places and drawbridges and things like that which swing. There are some other functions that may be useful for some (like medeval maps) such as func_pendulum for various types of traps authors of those kinds of maps like to put in their maps.
It may also be nice to include fire in nexuiz so fireplaces and torches could be made. I think Toen had some somewhat primitive fire so if that map got into Nexuiz, and it is a very good map, we would have something more. Toen also had whimiscal models of torches and brasaiers. It also had organic undulating shaders. All these would be useful and wonderful to have in the release.
Other models which might be nice are skeletons in diffrent poses [straight, shackled with hands above head, impaled, etc), skulls, bones; ones that have no blood on them.
If need be there are probably some opensource projects which allready have made some of these.
It is good to make and bundle these things with this opensource game because it gives more material in the hands of mapmakers who build upon it.