I agree whole heartedly, I refer only to those situations when an estimation is all you need. At my service, we use palpation frequently with BLS patients when calling the vitals in to the receiving facility and a full set of vitals is just not viable with the timing.
Our service requires us to get at least two sets of vitals for every call, so if we have a 4 minute transport (which does happen sometimes), BP/palp becomes a great option due to the fact that most of our transports are on the highway and it's a lot quicker. Palpation fulfills our charting requirements and, like it or not, does give the hospital a decent idea (key word, idea) of the progressions of the patient's condition.
That being said, I want to be clear that when I say "bp by palp", I don't mean "pt has a radial pulse, therefore his bp is 90/palp". I mean, putting on a bp cuff, increasing pressure until a radial pulse is no longer present, and then releasing presssure until the radial pulse shows up. I think it goes without saying that this method isn't always the best idea, but palp is often viable, at least for our service.