How people feel about having kids doesn't seem to be a uniform thing. The majority of parents certainly seem to love their children, but I do see a lot of mixed opinions about whether they love being parents.
In my peer group, it's been about 50/50 between people who seem to really enjoy parenthood and others who are struggling. There are many reasons for struggling, like how they or their spouse handle the stress and how much help they have or pay for. But the biggest one is that kids largely take up a lot of time and energy.
It's hard for someone to expect that they'll enjoy parenthood when they look around and see many parents who are unhappy.