It's pretty simple.
I also have two kids under 12 and their first reaction to any screen is to use it as an interface and look confused when it doesn't work :D
(I use an MBP myself and do find the desire to have a touch interface like her Surface)
It's really something that is useful in a small percentage of cases but really helpful in those. I wouldn't want to miss it. Lenovo even does matte touchscreens so there is no disadvantage (I hate glossy screens so Apple isn't an option for me either way). Usually glossy is the tradeoff you make for a touchscreen, but not in this case.
also not sure why you'd think ppl wave their hands in front of a touch screen all day blocking their view. most ppl are capable of moving their hands out of the way. it's not clear if you've used a smart phone before, but it's the same. though, i imagine if you did, you'd do as you imagine others do with a touch screen.
My local library has a big sign on their self-checkout computer explaining the screen is not touch screen, that you have to use the mouse.
I still touch the screen. Every single time.
That said, I'm not sure I want my desktop to act like a kiosk. Maybe?