... Think of it in terms of a woman's orgasm. If the guy can't cum from regular intercourse, how would that make you feel? If, in order for him to have an orgasm, he needed to pull out and stroke it with his hand.
I get your point but I think a better analogy would be that you have to keep stimulating, say, his ear during intercourse in order for him to cum. I could live with that. Especially if rubbing his ear alone would take him close but rarely all the way.
In a highly aroused state, I can get myself off with just rubbing my clit and using my imagination, but most of the time, it's the combination of internal and clitoral stimulation that does it for me.