I hate to be jaded, but why are they doing this? It's not out of the goodness of their hearts or to give us the convenience of changing our email address. Is it?

conjecture - retention of a generation? If i had deathfromtheside[at]gmail, then i grew up and was too lazy/non-tech/busy to set up a new account for janesmith[at]gmail?

Probably competition from other services