I think I see what you're getting at here, and with some clarification, I agree. I think that you're being a little bit too vague about the classification of comedy because comedy is inherently is an incredibly diverse medium whereas, as far as I can tell, you are referring very specifically to romantic comedies that were made under the Hayes Code.

Due to the fact that they were made under the Hayes Code, they had to swing back at the end, because that was part of the Hayes Code. If they did not swing back at the end, they were not allowed to be distributed, and thus made no money. Not making money made the people in Hollywood very angry. This had nothing to do with comedy as an inherent medium. In fact, if you look at other comedy being made during the same time period-- for example, the dregs of vaudeville and Borscht Belt comedy, which was the most popular at the time outside of film-- the door very rarely swung back, as it were.

I would not say that comedy is either an inherently a liberal or a conservative medium. I would say that comedy is, however, an inherently comedic medium. I would agree that romantic comedies coming out of a time when the incredibly conservative Hayes Code was in effect are incredibly conservative in some respects, especially in the respect that you refer to, with everything returning to "normal" at the end. I would go further and say that romantic comedies of today still follow this formula because their predecessors have influenced them, even though the Hayes Code is no longer in effect. I don't think that has anything to do with inherent properties of comedy, though.