Can the Iron Islands be worth the hassle of keeping them? Their attitude "We do not Sow" and the geography of rocky wild swept islands can't be very productive. I imagine they scrape enough food to survive but can they really be making enough of a surplus to be payin much in taxes to the crown?
Culturally they worship a different god and they don't tend to marry outside the islands.
They may be good fighters but would they make good soldiers in a regular army?
I can understand trying to keep them in line but there doesn't seem to be a garrison of Iron Throne tropps on the island to keep them in line. They seem to be left alone as long as they don't rebel.