As a woman I can tell you that I love to do that. But this is a recent and somewhat new development for me.
When I was younger I did it to please him, but it took all I had to do it. Now is a completely different story.
I think there are a few different factors to this actually. One, I had not done it for probably well over ten years, so it was like a new thing, and with age comes knowledge, and a medical background doesn't hurt either, lol. Knowing more about male anatomy and how it works and why the pieces are where they are makes a big difference too.
Also, the ejaculate doesn't seem to taste so strong/nasty as it has in the past. It's more of a sweet taste. Could be what he eats, could be his genetic make-up, or a combination of both?
Another thing, aging not sure if age play a factor or not, but younger guys seem to cum a lot, older guys not as much. Since we are slightly older, I no longer receive a mouth full, but rather a nice taste, easily swallowable.
And lastly, I honestly believe that how you feel about the guy also makes a difference in things like this. He told me that out of the women he's been with, only one would even let him cum in her mouth, and then she would spit it out. So, I am a first for him. He has told me that he loves this and is one of his absolute favorites. I love him and I want to please him because pleasing him pleases me.
Just a little from a woman's perspective.