"And, what about the FF that books 6 months out but loses out on a decent seat because of once-a-year flyers who cash in miles three weeks out? "
On long haul it isn't a problem. BA allocate approx 30% of seats for general pre assignment. When that threshold is reached and you try to do an assignment then, if a regular non status person, you cannot get an assignment till OLCI. There is about another 30% of seats that can be pre-assigned to Sapphire or Emerald members.
If you have status then you have a v good chance of getting a decent seat unlike the US model where it's every man for himself so the last minute traveller can end up with dire seats since all the decent ones were taken by cheap v advanced purchase fares.
On shorthaul, the system seems to automatially assign seats ( at least for status members ) for when check in opens. Last economy short haul flights I have been on I have gone to OLCI and found that I had a window seat in the 2nd row of the cabin.
Works well for me and better than the AA approach imo
Then again there are lots of other reasons why I wouldn't normally use AA long haul. I find them an inferior airline
Dave