I feel like the reality is that most non-bitcoiners in the world will be onboarded using L2 and likely will never touch a UTXO.

Trying to make things 'easy' or to build in 'safety nets' to base layer is the wrong move I think. I think it is better to build vaults and covenants etc in L2 somehow: If there is a market for it people will use it.

Base protocol needs to be unforgiving and absolute. You either have the keys or you don't. If keys are taken and funds are moved, that is just the way it is.