BMI are not fantastic and have not been so since the rebrand where "BMI" was not an acronym and "didn't stand for anything". A truer word was seldom spoken....
Whilst it's true that BMI failed to identify and target its market, and this is probably a fundamental reason why they are losing so much money due to poor yields and loads, they are, from a passenger perspective, a fantastic airline.
For sure other airlines control more than 56% of slots at their home base, that doesn't make it healthy. The national carrier in its own country invariably has a dominance which leads to the high handed and arrogant attitude that makes it enemies in its own country. The plus side to that is if I fly SAA out of JNB and they have a tech delay I know they are more likely to find a quick solution than another carrier.