I'll never have biological children of my own and I'll never get to use that benefit. From a strictly selfish standpoint, it stings a bit that pretty much all my heterosexual friends and coworkers, male and female, get a minimum of 12 - 36 weeks of paid time off that I'll never get.
Having said that, I'm genuinely happy that they get it, I think it's a shame that 12 weeks per child isn't a minimum standard for paternity & maternity leave. In the professional settings I've worked in that offer paternity leave, I've never experienced a coworker complaining or making fun of a man taking paternity leave, nor have I ever heard of a man NOT taking paternity leave when it's offered.
The places I've worked that offer it also usually offer flexible leave, so it's very common for new dads to take 4 - 6 weeks off at birth, and then work a reduced schedule for the remaining time until they're out of leave, after which they return full time. Even some of the moms are doing that as well, basically maximizing the amount of time that at least one parent is on leave and at home with the newborn.
But, outside of professional settings and particularly within conservative/Republican family and acquaintances, typically lower-to-middle class people, they act like paternity leave is ridiculous. My dad laughed out loud a while back when I mentioned I was taking over a new project because my coworker was about to go on paternity leave "What? Are you serious?" In my opinion, "toxic masculinity" aka stupid, ignorant, and useless concepts of overly rigid gender stereotypes is where this type of opinion is rooted. That and probably a good degree of jealousy.