I have to agree that if they were all holodeck adventures it would have been a big mistake. It would be hard to take some of the missions seriously if they were just on the holodeck. I mean, we're already playing a game, which we know isn't real. Now we need another level of not real inside something that's already not real?
Alright... I just wanted to seek opinion of the community and it seems all (or most) lead to keep UGCs as 'real' missions and not holodeck programs unless the author intended to do so. That is besides Holodcks on board would be awesome to at least replay missions the way we now can from the rady room.
I'm of the opinion that, as they are now, UGC missions are real game missions, especially in light of the new wrapper NPC for Foundry missions. I do believe, however, that the addition of a Holodeck to our ship interiors could open up a different facet of UGC, as some authors could intentionally design missions specific to Holodeck play. If we could get all the art assets and costuming needed to do period pieces, etc, that would be really amazing.