At a difference in price of $3, as long as you think you might be doing it, why not? For $3, it's worth it even if you might just want to go into EPCOT one night to eat at one of the restaurants.
Think about this. The 7-day MYW with park hopper costs just SIX DOLLARS more than the 5-day MYW with park hopper. (Even a little less for children's tickets.) So, for just $6 more per ticket, you could buy a 7 day magic your way. If you use it every day, great. You just got two full days in the park above what you planned (a more than $100 value) for $6.
Now, suppose instead you decide during your trip that you don't want to use all 7 days. So, you only use 5. At the end of your trip, you'd have the option, for $58, to convert your tickets into never expire tickets. So, for $58 (less than $30 a day), you'd essentially be purchasing 2-day park hoppers (a value of nearly $160) for $58. (Of course this only makes sense if you think you'll ever return to WDW.)
