For me I don't think we should drop it from our vocabulary, but unless you're paying attention to the PPM you could be wasting your time. The podcast @HighVoltageMan linked above has some really interesting information on the contribution from the grains and why you probably need to think in terms of ratios (as well as PPM) when you're targeting a flavour/perception with your salt additions.
Does the water calculator here make any attempt to add the various mineral contributions from the grains? I can imagine it would either be a simplification, so possibly not worth doing or a massive, ever changing, challenge.
I agree about the rather dramatic action to drop something like SO4/Cl ratio from our vocabulary. If there is evidence that we should, I'd really like to hear from the advocates of such action the basis for that. So far, I haven't heard anything substantive. However, I do agree that focusing on the ratio at the expense of PPM is not what I've read anywhere in the realm of those who should know. I just know that when I started to use it, I got some pretty convincing results.