I sense that Afpex has become a kind of "bashing" issue, just like Mode S became a "CAA bashing" issue.
Regardless of the rights or wrongs, people rally behind easily identifiable causes
The real issue with Afpex, in most (not all) situations, is that many UK pilots are not up to speed with the internet and the most basic IT skills.
While I agree with you IO, it does seem to me that AFPEX has shot itself in the foot with it's addressing.
Pilots are simply not trainned to address flight plans, and have little knowledge of it.
It's also something that should be extrememly easy to computerise. You've only got three pieces of information:
Departure Airport
Arrival Airport
FIR's crossed.
Each of these has a set of addresses that are required to be addressed. Why can't the software simply have a list of them, and insert them automatically based on the information supplied?
I think that would solve 95% of the complaints.