The boomers are spending that money, on rising health care costs, among other things.
I currently live in a country with subsidised health care, so is maybe this is an American millennials thing?
Getting $100K inheritance when you are 50 might be nice, but it isn't quit your job money. And most millennials could use that money now to get through college or put a down payment on a house, not 10-20 years from now.
Should 100K be retire money? It seems like a great boost to whatever you have earned. Most boomers I know are in their 60s/70s, so that may be regional but I don't expect most have a lifespace much longer.
And yes, many boomers still support their children.