You cannot tax an event, an event has no monetary value. An event may trigger a tax, in this case the wealth of your estate being distributed.
Dude, I am not trying to break your balls here, I really am not.
You started this thread with a question about tax strategy. For the past 200+ years, wealth taxes have been illegal. For the past 200+ years excise taxes are legal. Excise taxes are defined (in part) as a tax on events or activities, that includes the event of you dying and dividing up your estate. That has been the case for one whole helluva lot longer than Roth IRAs have even existed.
Now, if you think the tax laws will be completely different going forward based on an interpretation of law that exists solely inside of your head...knock yourself out! I mean that sincerely. Go to the mat for what you believe.
But I humbly suggest you'd be a lot better off using words the IRS way defines them instead of coming up with your own secret definitions.