When a guy has an orgasm, it's obvious. When a girl does, it's not... unless she squirts. So squirting takes all the insecurity of wondering if you made her come out of the situation. Plus it's a subconscious bragging thing, even if we never tell anyone else, knowing that we made a girl squirt.
How would you feel if a guy slowly and sensually peeled down your pants and panties and started squeezing, massaging, and kissing your Butt cheeks. And then gently spread them apart and starting licking your Butt Hole like an Ice Cream cone. Would you like that?
And I think guys like it for probably several reasons.
One would be that it's pretty much like their own orgasm. They have an orgasm and something comes out. So when a woman squirts I'm sure it just lets him know that the woman has come. No guessing. No wondering if she is faking. He just knows.
Plus, I think it's toted as the ultimate orgasm for a woman. Like the highest pleasure a guy can give her. Not all girls can do it either. So if a guy feels like he got her to do it, then it's like not only is he a good lover, he is one of the best lovers. He gets to go to a different level of awesome cause he is one of a few guys that got to see something happen and was responsible for it.
I've only squirted once or twice during intercourse, but I squirt all the time with toys or when being fingered, my one ex was obsessed with getting me to squirt while he ate me out, I never understood why, and he could never make it happen in the end.