I suspect that one of the key problems is that all the politicians and mangers, shareholders and non-execs that have any say in ANY of LHR's goings on - do NOT transit through. It is the terminus!
I have lived in West London and West Hertfordshire for 32 years, always within 40 mins drive of the place. Before that, with going to South Africa a main destination, I have been using LHR for 46 years but only ONCE have I had to transit through it.
On that occaision (1999) knowing what the place was like, I caught an earlier inbound to allow the time and actual came landside to see people. On the return I did not but waiting in T2 to go back to MUC, the roof in the main departure hall was leaking ...
So, I don't mind LHR - because I don't us it for Xfer. Some of their bosses should try it!