Why not??
A surprising number of people are simply unaware of the options they have flying outside London.
Case in point: Most TAs (!!!) in the Midlands will look at LHR flights when you walk into the agency and tell them "I wanna fly to XYZ". Then they'll suggest KL, LH or AF with a connection (as they usually are a bit cheaper than BA) when all of them have loads of flights into their hubs from BHX! I am convinced that many inexperienced flyers have been subject to this circus!