Marriott doesn't change guests. Individual hotels charge guests. The notion that Marriott (or any other hotel group) is going to somehow force all of their hotels to charge this type of fee is a bit ridiculous. Individual hotel owners don't take kindly to micromanagement from distant city (or distant continent in this case).
There are very few issues where a hotel group will force their franchises to do something. Aside from life-safety concerns and adherence to brand standards that are part of the legal franchise agreement, someone like Marriott Corporate has almost no leverage.
If this issue is so concerning, you should speak directly to the hotel management at each hotel you frequent. Maybe if you're lucky, you'll find an Operating Managers or General Manager who finds kids as disruptive as you do.