They already do. They've removed the old tomestones I collected and, while some of them are moved to poetics, others are moved to hunts and I no longer do hunts. Even the conversion they give you means you still lose out on some as it's not a 1-to-1 conversion.
Obviously they should warn people ahead of time to let people decide if they want to do something with their "excess" gil before the cap is lowered. Or just make it so you can't gain more gil until you're below the new cap.
Again, I'm not seeing the problem with having excessive gil. In fact, the people I usually see having problems with "undercutters" are usually people who would have enough money anyway. So much so, that one common solution is to buy out the competition and resell at higher prices, which would seem to exacerbate the problem of having "excessive gil" if it really was a problem."Gil is meaningless" past a point where you have enough to buy everything in the game without making a significant dent in your own funds. Removing ALL gil sinks instead of creating more will exacerbate the problem by creating more and more people with excessive gil amounts. Again.. the system requires a sink for those who have too much not an increase in the cost of playing in general. The problem right now is it has to be heavily expensive.. but not contribute something inequality creating or advantage granting. Also it cannot be something that only the super rich have access too as then it will INCENTIVIZE money hoarding and brew complaints about gating. ... I'm still at a loss as to what that could be.