Here is a possible fix that will probably make most gamers (of all platforms) happy. Here is my wishlist...
1. Give the PC players what they want and give them Sandbox 3 in all of its glory.
2. Give console players the option to download it for free if you link your gamer tag or something along the lines of that.
3. Give us a map downloader similar to Halo's file search.
4. If possible make it compatible for the mac because I sure as HELL don't want to go into windows 7 every time I want to make a map.
5. Possibly have it accessible to everyone (even people without the game, they might have a lot of talent and you lengthen the game life.)
6. Maybe update the game on consoles so that all you do (helping with the verification thing) is plug in your console and edit on your computer but play on the console (due to some bad computers).
7. Do something like bungie where if there is an extraordinary map that stands out from the rest, incorporate it into the multiplayer experience for all to enjoy.
This way you have a happy community, creative juices flowing, your training people to have a possible future in level design, and your lengthening your product a little longer on consoles and PC's. Either that or only give it to PC's and make your console community angry.
(P.S. I might have said some stupid things but please just point them out, don't be a douchebag and troll about them)