If you should ever need to cancel a reservation, it might.
Let's say you normally travel in September. If you had an April use year, and you should have to cancel for some unknown reason (more than 30 days out), you would still be in the 100% banking window, and could bank all of your points to the next year if you couldn't reschedule before March.
However, if you had reservations for March, with an April use year, and had to cancel (after the banking deadline has past - but more than 30 days out), you would have to use the points by the end of March or lose them.
Some people recommend that if you always vacation at the same time each year, you should get a use year a few months before your normal vacation time, so JUST IN CASE you should have to cancel your ressies, you'll still have time to bank the points.
Disney will sell you a different use year than the one they are currently selling, if it is available.
Hope this made sense.