I never said that BA was faultless, and getting stuck in other airport traffic is simply a consequence of being at an airport and from a surface perspective Heathrow is better arranged than Gatwick as the taxiway crossings are all underground. In an ideal world, you would build a new airport with no remote passenger gates but T5, and the new T2 are constrained by their position within the runways, and the airport itself by only having two. Neither of which are BAs fault.
The high J 773 can take a while to board, Club is over half the aircraft, but for boarding purposes they should be using dedicated buses for Club/First and then sending the rest, but it will still be 45 at a time, so whilst I can absolutely see where you're coming from re waiting to get down the aircraft the queue actually starts in Traveller Plus as most Club passengers just get on and sit down.
And if you think you have a walk up and down the aircraft, I am usually on the 773 working from Doors 3 and easily walk that cabin over 200 times a flight.
Americans are always slow on steps...they simply don't have them because their airports are all the size of Lincolnshire.It would complicate the boarding process/security protocols, but there's perhaps a case to be made for using a rear door for boarding from the back without impacting the business priority...