a sort of inflation of adjectives

That's a beautiful way of putting it, Alex. So true.

Open challenge: can anyone produce a pithy little word (and no taking the pith) that has the above definition?

three sizes of soft drink: large, extra-large and super-size
Haven't seen that yet, but there's definitely no such thing as a "Small" Coke. It would be Regular. No doubt that term will at some stage be considered too nondescript and colourless.