A Level Editor would not only help the longevity of Borderlands 2, but it would also help Junior Level Designers improve on their Portfolio, helping them for a future career and/or fulfill one of their favorites hobbies.
The request here is a simple, a fully functional level editor which permits it's users to create maps, edit archetypes/attributes (modifying enemies, creating custom quests, creating custom character abilities, ETC), create gametypes/scenarios using the Kismet editor and visual effects using the Cascade editor. Enough abilities for them to go beyond strictly map-making.
The production time for such a simple tool shouldn't be too cost productive for Gearbox. Please sign if you wish to see user-made and free of charge DLC, Maps, Gametypes, and much more.
More information: CookedPCConsole is the published build for Borderlands 2 PC. While it greatly helps on improving Loading times and game filesize, it entirely strips the editor code from the game. This build is what prevented the community to unlock the same tool, which was previously achieved in Borderlands 1 with a different build.