I switched back and forth between "with account"/"without account" a few times now and it seems to work just fine. I stay with the no-account state, as it not only removes the nags, the interface is actually much cleaner and more logical

No idea about Lens, because I never used it. Aren't there webapps or web services for everything these days? I do everything that I do only occasionally via webapps. Barcode parsing for example.