Andrew, certainly true that listing age-graded performances in addition to the actual performances wouldn't be an issue. It's kind of like listing some of the other auxiliary data you often see in results. Along with pace and intermediate splits, go ahead and list your PLP. Big deal. However, as you mentioned, basing rewards or official placings based on this creates a lot of problems. I'm not a fan of anything that takes away from that raw, head to head competition. I always think of my Chicago Marathon finish. Someone who crossed the line something like 5 seconds behind me “beat” me in the official results because his chip time was a second or two faster than my chip time. To use the terminology already used, I was racing a ghost. I had no idea someone was a second or two ahead of me for one simple reason. There was nobody there. If someone was actually there, maybe I could have beaten him.
Rita, I think it's an interesting way to compare yourself to earlier years but, as my PRs have become less frequent (and in the past few years non-existant) I've found other ways to keep the motivation up. Trying to maintain as much as possible, competing with the people around me, etc. If age graded performances do that for someone, great. However, there are also other ways.
I have no problem with age graded performances until some 50 year old comes up tells me he's a better runner than me because he ran an 82% PLP while my run was a 79% PLP. My performance is based upon a professional athlete making hundreds of thousands, if not millions, of dollars to run. His performance is based on an amateur athlete out there just like most of the rest of us. Seem like an equal comparison?