I agree that while half the time you have to call the Elite line to get anything done (the World Perks reservation system, for example, can't split a reservation into Y OW and C OW, also often won't give you standard seats when there really are standard seats available), this new tool will save a few calls for me.
Not only can I choose Exit row seats now, but they also have suddenly opened up several "blocked" rows of seats for the flights I have upcoming. For several weeks, a MSP-PHX flight I have next month had something like 6 P seats available, nothing else. I was smelling a TCV!
But now with this new "View/Change Reservations" mode, they have opened up 2 full rows of P seats that had been "occupied" before. Interesting.