I don't have a problem with it personally. Though I can see it causing SE to have an exchange rate melt down while they try and figure out the value of gil to the plex with all the currant gil saturating the servers. The other thing is a general lack of items that would make players want to use it. There is no BoE tradable entry level raid gear, attunment keys, difficult to get sockets/augments, no spiffy items with special effects, no skill advancement after the level up. Unless you really need that hot new glamor or furnashing day one or really want to buy a run carry, or lightning strikes and a house plot opens up, the game has little to offer for a mass amount of gil.

What I could really get on board with though is a form of alternate rare drop currency in game, say Mog Chips or something that can be used instead of real money on the cash shop.