Note that if drawback 3. is so bad that it can't be widely adopted, this means that neither can the lightning network because it also requires interactivity.
Thanks for your insights! Regarding this point, honestly no matter how much I love Lightning, it's one of my biggest issues with it.
I've been looking for solutions (like BOLT12:
https://bitcointalk.org/index.php?topic=5383567.0) for a while now. The interactive element is eliminated once you run your own full node, but it's really a non-insignificant hurdle, especially for new users.
It's definitely easier setting a friend of family member up with a pure on-chain wallet, pointed to my Electrum server instance, at least for the start.
But I've yet to fully look through the solutions Grin, Litecoin and others came up with and judge what looks acceptable and what doesn't.