@Aero Mad
I think you're right in past. LHR now is about big international connections that can't be had outside, but that's not what BMI mainline is doing. BMI mainline should be doing what BMIbaby is doing - it's LHR routes can be had out of Stansted, Gatwick, Luton and probably Southend too now, granted not all of them and the quality of experience on BMI seems lacking lately.
I think you're right, they've lost direction entirely.