NCL-BRU
Don't forget that BRU had been dropped previously by SN and then re-instated. I know a number of people who having tried the alternatives and can't wait to get the route back (although I'm not advocating "treat 'em mean, keep 'em keen" as an airline route development strategy).
Also re marketing, I would imagine that they are aiming at very specific market sectors where the cost of time is high or the alternatives aren't attractive rather than the general public, so probably don't need the level of market awareness of the EZY/RYR.