While I couldn't understand every point in your post and what you mean by "Lazy tanking", it is certainly not advisable going into Brayflox NM being a Marauder. Now THAT would be a reason to be called a "Lazy tank", because the Healer would automatically assume that you delayed your job quest and have not obtained your Warrior crystal yet. You wouldn't be happy either to find a Conjurer instead of a Whitemage in your lvl 30+ group because it means you are missing out on Cure 2.

Btw, Defiance does not only increase your HP but also increases the amount of heal you receive by the same percentage. It is usually mandatory to have it switched on to easen the burden on your healer.