The offering of bmi is not a loco airline and it is a higher cost operation.
SAS tried low cost with Snowflake, and it was a huge failure (one of many SAS failures). It just seems to me, as an outsider, that having two 'sister' airlines based in one airport, each with its own management, brand, bookings, and basically offering a similar buy on board product doesnt make sense.
Now that they are even sharing aircraft, with the Bmi fleet flying Baby routes, it just gets way too complex. Wouldnt it make sense for the group to have one brand - and do it properly. Surely some of the bmibaby markets would connect into bmi flights at manchester to scotland and the americas, which would help the fleet. I have flown with baby and bmi, and could not really see a difference from a passenger viewpoint.