I suppose the lack of "decent" facilities, particularly food wise, must have something to do with royalties payable to airport authorities. Independent operators maybe don't have the wherewithall to tackle this.
This is a sad fact for nearly all major airports, even in countries where you would think there was no excuse. Last week, for instance, when faced with a 5 hour transit in Sydney, I left the airport and took the ten minute taxi ride round the bay to Brighton-le-sands, where I had a very passable seafood lunch, overlooking the bay and the planes taking off and landing on the other side. Very civilised.
I agree with Globaliser that probably the only food outlet of any class that I can think of is at LHR T3 (Chez Gerard), which was still there last month when I passed through.