Heathrow has the most aggressive Skytrax campaigning I've seen (note: some compared with nearly none) in the 7 of the top 10 airports I've been to, which might have something to do with it. It's definitely not in the same league as the likes of Incheon and Hong Kong in my experience.

One serious issue in Heathrow is that gate numbers are not shown (not even printed on your boarding pass) until 30 minutes before departure, and the gates are supposed to close 15 minutes before departure, but it takes 20 minutes to walk to some of the gates from the waiting area. Of course they bend the rules so that people make it to their flights, but what happens when they don't?

They've probably ranked up the value of diversified shopping. They would explain why rubbish large airports get ranked miles above small, efficient Australian and Scandi airports.