Honestly can't believe some of the people here are even allowed to have kids
The reason the iPad is dumbed down is because desktop operating systems don't do touch well. I have a Windows tablet and Metro hasn't caught on nearly well enough to be used primarily. The desktop side is just a joke in terms of UI for touch input.
I agree also that some people should be restricted from having kids.
The reason the iPad is "dumbed down" (using your words) is because operating systems did not do touch well IN THE PAST, but certainly this is subjective and I'm just putting my opinion out there. Windows 10 has come a very long way and is quite touch friendly. Just the fact that you use the word "Metro" clues me in where you are in the windows timeline, that term is what 2-3 years old? Windows 10 has moved so far from those times.
But there are other reasons for iOS existence as well, initially at least. Battery life, size, weight, thinness. I will always be indebted to Apple for the revolution they made by introducing the ipad, I'd shoot myself if I was stuck with a windows tablet from 10 years ago. Big, heavy, thick, clunky, terrible OS for touch, poor battery life, etc. But times change, and now windows tablets are virtually neck and neck with ipads and the reason for a dumbed down OS isn't anywhere near as important. Let's also not forget that Apple would much rather you buy multiple devices from them, they want you to buy an ipad and a MacBook and combining the 2 would hurt their sales.