Farce? What has the encoding scale have to do with anything? The data isn’t in 256 steps yet you feel a 0-255 scale is professional but 0-100% isn’t?
FWIW, you can produce 0-255 values in LR4 for Melissa RGB while soft proofing if that is somehow useful. I don’t see how a value of 255 or 100% to define the whitest white is in any way more useful or less professional than the other. In fact, 100% white, 0 black seems to make more sense considering the actual data. Equal values of either is neutral.
Just because someone was brought up with one scale, doesn’t make the others inferior. The metric system, (which I would submit is more intuitive than the US standard system) confuses those brought up with the US system. The opposite should be true. That doesn’t prove that a mile is any less a professional metric to describe a distance than a kilometer!
In Photoshop, 24 bit CMYK is still 0-255 data but represented as 0-100% CMYK ink. That’s logical? Try telling an old time prepress guy that using those values are silly or not professional despite the actual data.
ACR has never been 0-255/Adobe RGB. The primaries are ProPhoto RGB but with a linear gamma encoding. The histogram and numbers are the same primaries but with an sRGB tone curve. You can build this as an ICC profile in Photoshop’s Color Settings, save off an ICC profile and load it into LR4 to get those beloved 0-255 values. Now are you going to export that data in MelissaRGB? And considering that any working space, Melissa RGB, Adobe RGB (1998), ProPhoto will most likely get converted to another space (output or maybe sRGB for web), the numbers are going to change. So what?
Belatedly, thanks for the feedback. I knew I'd draw you out!
Wonder why they've opted for both 0-255 (when softproofing) and % in LR?