OP again.
This discussion has partially run off the rails from the original question into political philosophy on taxation vis-a-vis estate taxes, wealth taxes, etc. Not necessarily a bad thing, just an observation ;-)
I will note that my original question was intented to provoke discussions more along the lines of 'when I hit $XXX (the 'too much' number of your choice - as originally stated, my theory is that it's $10MM for a family of four), I will do Y' (VOLUNTARILY, not because of some government mandate) and for us to consider what can be done and how - via QCDs, CRTs, CLTs, etc.
While I'm 'here,' though, I'll throw my $0.02 (after taxes) into the mix. I'm very favorably disposed towards very high estate taxes. Why? Not because I'm a raving mad socialist (well, not the raving mad part anyway) thinking that we have to redistribute wealth, but because of the alternative.
In a rational system of government, the government calculates what is necessary for it to do, and collects enough taxes to pay for those activities and expenditures, modulo whatever is required for fiscal stimulus or restraint in order to achieve economic stability. (For example, extra stimulus during COVID economic crisis). The taxes have to come from somewhere. If people thought about the question in terms of 'who should pay for stuff - dead people or living people?' I think most would agree that having dead people pay for stuff is a better option. N.B. I don't propose that there should be no allowable estates or even that there should be a cap, just that we don't leave too much on the table when there is so much that needs to be done... for the living.
When it comes to the question of wealth taxes, I'm not a huge fan. Granted, this is possibly coming from a selfish perspective as I would be affected, but it feels like double taxation to me. However, it does seem to me perfectly reasonable for there to be some sort of 'asset protection fee' that the government charges for all the services it provides to protect assets - functions like the SEC aren't free. Now how much should that be? Well, I'd say that the gov't does more for my money than Vanguard does, and they charge 0.03% or so... maybe 0.1% would be reasonable? (That would raise $85 billion a year by the way, which wouldn't cut the annual deficit by even 10%, so we're not talking about a radical measure here.)