Gil is handy for times when you want to throw gil at a problem instead of time. Let's say you really wanted the Hand of Creation title. Instead of farming all of the materials in Diadem, throw your gil at the MB to get what you need. If your crafters are already at the point where they can make the next tier of gear (6.4), you won't be spending gil to get gear anymore. You'll be making gil. Craft two sets of gear and sell one. You'll break even or make a profit. You'll need to keep some gil on hand for melds in the future (takes money to make money).

Honestly, if how much gil you need is probably tied to how much you care about glamour, housing, etc. You don't need that much gil to play the game. It is the "extra stuff" that drains your coffers.