The problem with BRU is that the landing fees and airport taxes are so steep that it would not be possible for "low cost" carriers to make the prices good enough to attract the PAX.
BRU and its brand new terminal is like a ghost town these days, it's about time that the aiport owners gets their heads out of the sand and make the prices lower not just to attract the "low cost" and major airlines but to assure its own survival too.