The same can be said of toddlers. Kids lack experience, so they often make up with reasoning skills (that's why there are so many famous child logicians). I'm not sure it's "inhumane" not to engage with them rationally; my sense is that adults fail to see how well children reason because they focus on the conclusion.
But, for sure, we're missing some of the greatest parts of parenthood if we don't engage in philosophy discussions with our kids.