Mimblewimble has the nice property that funds can only be received after proving the ability to spend them. Or as I’ve seen someone say “You can’t lose Grin”.
Bitcoin lacks this property, but users often jump through loops with additional transactions of tiny amounts to try emulate this property and reduce their fear of funds ending up lost.
Non-interactive transactions are a departure from Mimblewimble in giving up this property.
I think the main culprit of current poor usability is the failure of exchanges to support TOR and slatepacks.
With regards to a finalize step being non-intuitive, I would prefer that the we see more use of the invoice workflow, where the three rounds can be called Request, Send, and Receive.
The initial slate sent in request can be accompanied by the wallet address, giving the sender a choice whether to complete the tx over TOR or by sending back a slate over whatever medium was used for the request.
One problem we have with invoice workflow is lack of payment proof, but that can be solved using the techniques of Integrated Payment Proofs.