i play neverwinter alot and i have to say that The Foundry is a good damn "invention". You have but a limit of used objects (500 i think), but yeah. you can create your own quest-series and also maps.
The background is that the main content of Neverwinter not long enough is (technically 60 hours and you on the highest level of the game with a good gear) and they created the Foundry. People can make their own questseries to entertain the users and i have to say ... many quest are epic as fuck, i never played a lot of questseries in an MMO but this is really awesome. Many quest are very hardly but it exist simple quest like "kill that" or "bring me that".
And yeah i think the developer make it to avoid modelchange or exploits for gauntlygrym (pvp area), or just want to be special or what ever. i like the idea! i mean it's like the G.E.C.K. from Fallout 3 / F:New Vegas.
For roleplay it is perfectly, a german roleplay group make their own area's like we in noggit.