Possible candidates for getting their own identify are polycarbonate (why bother if the BPA scare is going to put this plastic away?) polylactic acid (since all the PET recyclers hate the mixed streams), and LLDPE. They are also thinking of tightening up the definitions for each resin so that only a certain % of a coating can be on the bottle.
I certainly do understand that these polymers need to be kept separate. They are thoroughly incompatible with each other not only thermodynamically, but also in processing temperatures, drying requirements, screw design, die design... The only way to avoid those issues is to incinerate them all. The flames don't care. They are an equal opportunity oxidizer.
But this could rapidly go the way of stainless steel, aluminum and other metals. For steels, you have the 300 series, the 400 series, etc. Even with something like 316 SS, you can also have 316L (low carbon) and 316 LS (surgical grade), and of course other numbering schemes exist.
Sorting 11 or more grades of plastic would be overwhelming as it would require 11 separate bins, and could easily result in more people not even attempting to keep up with it and just chucking it all, which would defeat the whole purpose, wouldn't it?
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