@Kerrida - You're right and who's is gonna play GM-mode on their first playthrough anyway? Might as well release it a few weeks later like they did with GTA online.. Only working this time... The important thing is that there is a community that supports the tools and that the message gets out there.
Well I know people that got Mass Effect 3 and never went through the actual game, only focusing on the MP. Yes, Mass Effect Multiplayer, which ca be fun, true, but clearly not a fully-fledged MultiPlayer game in its own right =)
I could totally imagine people getting DOS2 only for the GM mode myself. I even think some people here said they were successfull in convincing their otherwise uninterested friends to get the game just for the GM mode, or something like that. This is a serious feature and selling point if done right.
Although I agree it could be released a few weeks later as part of a DLC or something, I'm not sure it should. It's best for such a feature to be a part of the game right from the start, rather than be "the DLC feature", which is quite pejorative =)
The Brotherhood of norD is love, the Brotherhood of norD is life.