The whole "free childcare" angle is silly. If you want to credit that, credit OP for providing free access to grandchildren. Families do things for each other. Doing those things doesn't make silly energy wastage OK. Yes, waste the energy to maintain the peace. Do it with a smile on your face and without complaint! But feel free to snigger behind your hand. OP, I'm sniggering with you.
Some families do things for each other, some do not. Some will do some things but not other things. Neither my parents, nor my in-laws, ever once offered to provide free babysitting for my kids. In fact, they made it crystal clear that in both cases, they had raised a lot of kids themselves and were not at all interested in doing any more child care.
I went through eight rounds of chemotherapy without once having either set of grandparents so much as offer to take my kids to a movie for the afternoon. They live five minutes away, were in good health at the time and were retired. We don't have a bad relationship with them, but they have a lot of grandchildren and they were just done with anything kid-related. My kids were very well behaved, not loud or wild and they are respectful.
Not all grandparents are overwhelmed with joy with the thought of "free access" to grandchildren. They spent many years taking care of their own kids and now would much rather be golfing, boating or playing with their own friends. I think a lot of parents vastly overestimate the appeal of their own offspring. It's nature's way of making sure you take care of them. Many of my friends have parents who are equally disinclined to take care of grandchildren.
So yeah, I see grandparents providing free help with childcare and household tasks as a huge gift not to be taken lightly.
I also disagree that the parents created a situation where they are now intolerant to cold or heat. My dad was hard core mustacian. He built the house I grew up in with his own hands, and could make a penny stretch farther than anyone I know. Our house was freezing in the winter and we had no A/C, so it was sweltering in the summer. Now that he's old, he feels very uncomfortable in warmer or cooler houses and needs the temperature set accordingly or he is in distress.