Two adults with two children is doable with 2 beds. That's higher than the average number of children for a family in the US at this point. I know plenty of people with children (and I have children myself).

Airbnb probably serves you quite well, but you're a bit of a niche market for the travel industry, so it makes sense why your need isn't generally addressed. Hotels have to maximize their space, and the vast majority of people don't need kitchenettes.