We've all been doing it by using cruor to buy chocobo blinkers then NPCing them for gil for a long time now. The dev team should by now be well aware of this. It could be eliminated, trivially and without side-effects, by adjusting the NPC sale price of chocobo blinkers. But they have refused to do so. I can only conclude that the dev team is perfectly fine with the idea of converting cruor to gil.
However, this procedure is tedious and requires lots of inventory space. So I propose that an NPC should be added to convert cruor to gil directly. There's even a ready-made lore explanation--it's already been stated in the Voidwatch storyline that Jeuno needs cruor for its anti-Voidwalker efforts and is always wanting more. Jeuno is of course a very wealthy city, made even more so by the fact that they literally mint gil. It would be trivial both code-wise and lore-wise to do it and it would make our lives a lot easier. So why not?