For the better graphics

[seven]

For the better graphics:

-vertex paint
-bump maping
-specular highlights

optional

-new compiler of map and bots (without restrictions to the number of objects, vertex etc.)
-better use of the alpha channel. Increase the distance generate the graphic (j can't see good distant textures with alpha channel)
-dynamic shadow map
-soft bodies
-bones animation
-3d objects animation from blender or 3ds
-editor join the bots, map, textures, compiler and scripts. Use more 3d formats. (fbx, lwo, ase, blender format)
-shadow map from file without restrictions.
-support large textures (8000x8000)

http://www.youtube.com/watch?v=pCf1gyN-UfA&feature=related

[SharpestTool]

As my lack ongoing involvement shows a free project is hard to get big efforts going like the one you suggest--people are hard to keep around for them.  It's best for small steps.

On that note, to get you started.
-Bones animation really is only possible with skeletal models and OpenArena doesn't have any at the moment.  The engine supports the Raven MDR format but again no models exist.  (You could write code to dynamically add bones to MD3 models at run-time, but it'd be a nightmare to think about)

-Bots won't ever be incorporated into the "editor."  GTK Radiant/Net Radiant were made to support a wide range of games and bot editing is just a small subset.  Bots interact with the map through the "area awareness system" or AAS.  The AAS parameters for a map are created at compile-time by a tool called BSPC.  You can edit the AAS parameters from the radiant editors, and script their compilation with them, but the bots are edited in plain text files the engine uses at run time. If you want to be able to add bots depending on some sort of action in the map, you can do this through adding map entities--but you'll still have to write the code to support it on the game side of things.  RTCW Single Player does this, but its code won't mix will with the style of bot from Q3.

-Dynamic shadows have been done by Xreal and the ZeroRadiant editor. They break compatibility with existing assests.  Code in a way to check for the differences at run-time by map and you have that nasty little problem of existing compatibility solved.

The all-in-one editing solution really isn't necessary, most mappers have just learned how all the tools (radiant, bspc, q3map2) interact.  It's not perfect but it keeps each project from worrying about each game's stupid little nuances.

Good luck with building some MDR models.  There are exporters for various tools (blender, gmax, etc) out there. 

You should be encouraged that this stuff is possible--just you'll have to take some initiative to work from within and in small steps->OA relies heavily on upstream projects (ioquake3, GTK/NetRadiant, q3map2, bspc). To customize these in some grand fashion would have its tradeoffs and definitely impose a great project management overhead that'd make fromhell (fromhell) consider giving up in life and turning into a republican stay-at-home mom. 

So get involved and help make these ideas come to life.