The redenomination isn't supposed to be an instant fix all for the economy. It also isn't a one time gil sink, nor is it supposed to be. Everything is redenominated, not just player wallets.

It merely reduces the overinflated gil values of everything in order to simplify things a bit and allow lower quantities of gil to have actual value. In other words, this does improve the economy in the long term, albeit in a different sense.

As far as the rest though, yeah. Gil sinks are important to keep driving an economy.