About ten years ago when my parents were doing estate planning, they told me that they didn’t want to leave anything to my brother and his wife because they would likely waste it. Instead, they wrote their will to skip my generation (which is just me and my brother) and distribute things evenly to their four grandchildren (two are brother’s kids, two are mine).
That was fine with me because 1) it’s their money/their decision and 2) DH and I are doing well, so I don’t begrudge any inheritance going to my daughters. We aren’t talking huge amounts of money, maybe about $100K to each heir at the time. It may be more, or less, by now. DH & I are much better off financially than my brother, and my DD’s are earning much more than their cousins. $100K would certainly help either of my girls at this stage of their life; it would be life-changing for their cousins.
Recently my aunt asked me what I thought of my parents’ plans for their estate. I told her that as I understood, it was going equally to the grandkids. She indicated that was not the case but wouldn’t fill me in. So maybe things have changed. Still not my business. But deep down I know I will be disappointed if the will has changed to give everything to my brother or his kids, and my girls get nothing. (I doubt that’s the case).
I agree that parents can do as they please with their money and don't have any obligation to leave it to their kids.
I am also a huge proponent of having parents communicate their intentions to their kids prior to their demise---let the kids know what they intend to do with their money and explaining their reasoning (if they so choose), so that there are no surprises when they pass. This way, parents can deal with any consequences and maybe address/resolve (if possible) any conflicts among kids while they are still alive. This would lessen the chances of their kids harboring resentment or turning on each other upon their passing because of any perceived inequities in inheritance.