I don't think they film very many days out of the year. Also, while their kids are definitely exposed to the public, I don't see that much of their privacy has been sacrificed. Kate is a daily part of their life and we hardly ever see her. We've never seen anything related to their school life except a general reference to homework. Nothing at all related to what schools they go to, what grades they are in, what grades they GET, their school friends, etc. Actually, the fact that we don't see these things has led people to assume that they have no friends - which I doubt is the case. When I stop to think about how much I actually know about Will and Zoey's everyday life, it's not much.
Bill and Jen's mission with this show from the beginning was to "normalize" the public perception of the lives of little people, which I think they continue to do very well. As someone with a disability, I can honestly say they have inspired me to stop making excuses that keep me from pursuing my dreams. They've also inspired me to be unapologetic or ashamed of accommodations I need to ask for or to make in order to live a full life. (One episode immediately comes to mind - it was the time Jen went for a pedicure and needed a pillow or stool - can't even remember exactly - but after that I had my first pedicure in years because it gave me the confidence to ask the salon to make some adjustments to accommodate my leg issues.)
Bill and Jen continue to be an example of people who have not just accepted the hand that life has dealt them, but have lived a full and happy life in spite of challenges and are raising their kids to do the same. That said, the world is not always a kind place and I can imagine Will and Zoey will have their share of real-world disappointments ahead (if not already) - and maybe knowing that is why Bill and Jen give them a bit more leeway at home.
Also, I think they are smart for taking the opportunity to make some reality TV $$ while they can. Neither one of them seems to rely on it as their primary income (they both have continued to pursue their careers unlike many other "reality stars" who have abandoned any other form of gainful employment.) It's gravy $$$ for maybe a few weeks' inconvenience a year - and no one (including the kids) seems to be any worse off for it. It also appears they have taken the money they've made from it and INVESTED it in real estate. And yes, they took a loss in Houston, but that had more to do with the hurricane which they couldn't predict. They weren't the only ones who lost money because of the storm. I still think the Florida waterfront property was a good buy.
Anyway, I'm all for them riding this gravy train as long as it lasts. Good for them!