I stand to be corrected on this first point: I don't think that BA started dba? They bought a pre-existing carrier?
On this I am more certain, "Surely our national airline can ..." BA is not our national airline. Across Europe the nationalised airlines are being sold off. The UK government does not own BA, it is a plc with the only restriction that 51% (I think) of the stock must be UK owned.
I only had cause to use dba for one return trip, MUC~LGW~MUC. It was grim. Service and food and everything was poor. In the luggage hall, another pax commented to their partner that they had enjoyed far higher service on LOT.
OK, anyone can get it wrong but I was comparing it to MUC~LHR on BA that I used numerous times. The LHR service on the main line was very good.
Now that dba is back in German hands, they are more likely to get the changes in Terms & Conditions, I should say. Helping this is the fact that the German parliament has just voted for big changes on the financial front. These are changes that have been resisted for many years. It may be that the German citizen is beginning to see that times have changed.