Personally I think they're a waste of time.
I'm sure you've all heard of the whole exam reform thing that only ever seems to come to light in mid-august, and am sure you all know why. All thse politicians we hear about are constantly trying to draft up new assessment schemes, or add to old ones, i.e. the over-arching diploma and extra optional questions/5000-word-essays/reduction from 6 to 4 modules/presentations/access to modular grades for A-levels, respectively, and they seem to overlook that AEAs exist. I'm not so sure of the consequences, but wouldn't making AEAs a compulsory part for entrance to Oxbridge, ICL etc etc be a quick achievable solution for the current education exam system shambles?
The fact that AEAs do not serve this purpose, and that they don't count for university entrance anyway, in my opinion shows their uselessness. I am aware that Oxbridge occasionally make offers on AEAs but I applied to Trinity for entrance 2006 and was made a conditional offer with no AEAs attached. Whether this was because my school doesnt offer AEA exams, or that it is not Trinity's policy to make offers on AEAs, I don't know.