Well, considering that the response to all the complaints when the Ribbon was first introduced was that it was based on customer metrics, I assume the same would apply here. Indeed, I have to admit to having been a very rare user of File - Exit in Excel - I tended to click the application X until they broke that functionality. Now I shift+click it, Alt+f4 or use an Exit button on the QAT.

But, as Pecoflyer said, if you really want to know what someone was thinking, you have to ask them. Although I have no idea how you would contact the right person.