What they should really do is tweak the reward mechanics to where everything that gave xp would instead give tomes (or something useful) proportionate to what the xp would have been worth. Or at least a gil bonus to comp for the xp. So you can still do all leves and fates and get something for it. Lower level ones wouldn't get you very much, but as it is now, all pre-50 content is totally useless after 50.