It sounds much more like there just isn't room for MGP on the currency tab. While it may look to us like there's plenty of room, they've confirmed that they're introducing several new currencies in 3.0 (red chips, blue chips, etc), and space is almost certainly already reserved for those. So, rather than squeezing it in with the rest of the currencies, they introduced the Gold Saucer interface and put it there.

It sounds to me as if they're going to remove the currency tab altogether and introduce a seperate currency interface. Such an interface could have separate tabs for DoH/DoL currencies (like the chips) and DoW/DoM currencies (like the tomestones), and another for misc currencies (GC seals, MGP, Allied Seals, etc).