There was an interesting post a while ago from a regular longhaul traveller, who said that the benefit of using a ME3 hub was it meant that when he landed in the UK he was home; if he came via LHR he was faced with hanging around for an infrequent and unreliable onward flight. The addition of Ethiopian will make it even easier to avoid using LHR or any European hub, not because the terminal experience is poor, but because of the way the journey is divided up into manageable sectors.
As far as most of the UK is concerned, hub and spoke out of LHR is a ship that has sailed.