Maybe the clue is in the 'Connect' part of BA Connect. It's about the only thing to differentiate BA from the LOCO lot right now, BA will 'connect' you to another flight whereas the LOCO will blatently tell you they are point to point.
So when BA provide service to/from one of these non 'sensible' airports (which appears to be defined as being in the UK but not near London) you 'connect' to the 'sensible' airport in order to get somewhere via another flight. The LOCO approach appears to service airports in non 'sensible' places but will fly you to another non 'sensible' airport without any connecting. For some this makes a lot more sense, i.e the tens of millions of people who don't live near Heathrow or Gatwick.
Also, why do people consider the 'destination' to be in continental Europe. People in Europe might be a bit offended by that, they may think the destination is in the UK. If they want to get to anywhere outside London (for there is life outside the M25) it might just be more convenient to fly to EMA or BRS or LPL or NCL. London is an important city, sure, but it's not the be all and end all, and life is far better in parts of the country where you don't spend all your disposable income on a mortgage. The LOCOs are addressing that market, and if you look at their loads, they appear to be doing very well indeed. As we are not wasting all our money on mortgage interest we might be able to afford to fly to Europe when our London dwellers cannot.
I bet you once the FR and EZ network matures they will start integrated service just like Southwest does. They will then have a massive European network in place, which flies to airports with loads of customers within an hour's travel (about what it takes to get from the gate to the runway at LHR
) BA can connect you to heathrow from a shrinking number of regional airports, but what's the point of using BA if I can get within 50 miles of my destination anyway for a fraction of the price and avoid LHR in the process? BA connect might make sense if you are flying to New York from the provinces, but not if you are flying to Rome. Even so, you can fly nonstop to NY now from places outside of London, and look at the airlines moving to MAN/BHX for their long haul flights via Dubai and places.