Interesting questions, Chris
I don't think it's an instinct to reproduce as much as it is instinct to pursue pleasure, and I have no doubt that for a man, barrier-free offers the fullest physical pleasure.
I cannot physically tell the difference between a latex wrapped versus bareback penis during intercourse, so that part doesn't matter to me (all things being equal). Regarding the semen soak...
If I'm going to be dancing all night after or working all day after, I'd prefer to not deal with the leakage - please cum on my belly or breasts or whatever spot pleases you (except the eyes and hair!) or use the pretty plastic wrap
I suppose practicality overrules any sense of intimacy for me in this