I think there is a confusion with what the Dev Team refers to gil sinks and what we think they are for.

I believe any gil sinks introduce in the game are not for draining the current players of their wealth but instead measures set in place to stop new players reaching outrageous amounts of gil like the current playerbase. I agree with the Dev Team in wanting the rental chocobos to be highly accessible to anyone who wants to use them. As for keeping players where they should be, chocobos can be attacked by fiends, so that will keep most of low levels under restrain when exploring with their chocobos.