My two cents.
I can understand some of the reasons that could exist for not allowing the display of sectionals that are too far outdated. After all it is quite affordable to maintain the subscription, especially if I regularly use several charts. My biggest concern is that if the iFly corporation goes out of business, I would no longer be able to use the iFly.
If the iFly no longer displayed current information I'd likely purchase the required sectionals in order to have current, accurate information.
However...
Even though outdated, the iFly display will resemble the current sectional close enough to allow me to know where I am on the paper sectional I'd have to purchase.
I'd still be able to use the flight planning feature to have a colored line to follow to my destination, which could be a random waypoint if the airport is a new one not displayed on the iFly.