I'm a man and maternity leave does not bother me despite it being "discrimination" on the face of it. For one, maternity leave isn't really equivalent to vacation. Taking care of a newborn baby is very hard, exhausting work. To add to that, giving birth is a pretty physically traumatic situation that a woman does have to spend time recovering from.
Ultimately, no two people at a company are going to have identical benefits. We should try to be fair and equitable, but that means different things to different people, and is not always clear-cut. I can either wring my hands that someone somewhere may be getting a better deal than me, or I can actually go ahead and try to improve my situation. I don't see any point in trying to knock down women who want to be mothers because they may be getting a benefit that I'm not.
And finally, there are strong arguments for mandatory maternal (and paternal) leave from a societal perspective. I'm not going to rehash them here, but they're there if you really want to understand the other side.