But direct services from regional airports is not BA's business model. No-one would find it surprising that BA don't operate an extensive route network outside the capital. KLM, LH, AF etc treat UK regional airports exactly the same as BA - they're just feeder services to their long haul networks.
It's also not as if other national airlines aren't doing the same thing as BA - Iberia only operate from Madrid, Finnair from Helsinki, KLM from Amsterdam, LOT from Warsaw. Also, the reason why BA scaled back their operations from the likes of Manchester during the late '90s and early '00s is because of point-to-point competition from easyJet and other low cost carriers. Airlines that do operate extensive networks from multiple bases either face a lot less LCC competition such as Lufthansa, or are on the verge of bankruptcy such as Alitalia.