Or is there an assumption or recommendation that Bitcoin not be used for transactions that are immediate, such as point-of-sale?
No, this is an
assertion that bitcoins not be used for transactions that are immediate, even if a business is
already capable of handling the levels of fraud the current system would entail.
In fact, out of the roughly half dozen people running services I have either contacted, or who have contacted myself or John Dillon, nobody has actually asked us not to implement replace-by-fee.
Of course not. Until bitcoins become commonplace, the most common user of zero-confirmation transactions - brick and mortar businesses - won't really exist. If this change is inevitable like you guys claim, why not wait for it to happen naturally?
False sense of security.
The point of all this is that zero-conf tx should not be used for
zero-trust situations. But merchants will, because it "seems to work" right now. What we want is merchants to recognize this lack of security and decrease required trust, say, by having the buyer show ID before they walk out with the merchandise. Just like they do for cashing a check (which carries much of the same risks). As long as there is a way to use the legal system as backup, then they have appropriately compensated for the lack of security behind the zero-conf tx.
Merchants could learn the hard way, and then they'll stop trusting zero-conf tx. But if they do that, there's no reason any more to artificially maintain this illusion that they are somehow secure. Might as well just write it off now and let everyone start adapting now.