Game developers have no interest in updating tools. Why would they? They used them and didnt update them for there own employees. GTK is stable and you can use it now untill it has "written" support for JK2 if you know what your doing. For a tutorial see Jedi Knight 2 Editing (
http://jk2ed.jediknightii.net) JK2radiant is based off of Qeradiant beta 1.0 build 147. Thats about a 2 year too 3 year old set of tools. You can't use JED, or WorldCraft. Unless you like building a box which no one will play in. GTK will support JK2 soon, if you don't use it we look forward too not playing your map. Because when it comes down too it only good mappers use GTKradiant period when it comes too the Quake III engine.