Imo what you're saying is reasonable not just for kids but for everyone - we need spaces for outdoor recreation and sport. And that includes some amount of native grasses. That being said, if you go through a suburb, most lawns are not used for that purpose and certainly, almost every boulevard is wasted. Many neighbourhoods either lack public parks, or the parks are not safely accessible by bicycle.

That's where the whole nolawn discussion comes in: to stop making lawns the default. They have a place, but we're overdoing it to the point of pushing out native species and pollinators such as bees and butterflies.