I think it has more to do with the different things that they were planning on doing with both games, Ant. With Neverwinter Nights, Bioware's goal was to create a game with a versatile toolset and multiplayer capabilities which would make it as close to a PnP game as possible. They also threw a SP campaign with NWN which was, frankly, not exactly the cream of the crop. However, when multiplayer-wise, this IS the only game that I'm still playing years after its release(session 38 coming up tonight for a campaign that I DM). Toolset-wise, it's easy to work with to the point that I can change and adapt a module weekly on the actions of the players. Scripting-wise, it's pretty powerful, allowing for quite a few nifty things as well. However, because the toolset is an important aspect of NWN, some things had to be simplified, and thus, enter the limited area building via tilesets and placeables. For me, it's perfect, I can easily put areas together and create dungeons for the players to adventure through. For those who want to do more in crafting their areas, it's a nightmare.
With KotOR, Bioware's sole purpose was to create a single-player campaign. Gone are the limits with building a campaign with a toolset that's meant to be friendly for an end-user. Now they could craft something where the only real limits were the tools and software that Bioware had.
I think I've read that WotC basically asked Bioware to create a 'Build-your-own-FR-module' game, so that is why the toolset was delivered with NWN. Lucasarts pretty much wanted a single-player game that could also be played on the X-Box. Hence, no toolset comes with it.
However, this does not mean that you can't edit KotOR. At swknights.com, there is an editing forum, and if you're familiar with NWN, it is quite possible to edit something together. Unfortunately, you'd have to use the existing areas, I don't think there's anything yet to build new areas(which would most likely have to be built using some bloody expensive modeler or something). I have done some experimenting, and it's really not that difficult, although it's anything but userfriendly. You basically have to position everything by hand by typing coordinates via GFF editor. Scripts can be compiled as well using the NWN tools.
The answer is maybe.