Dude.
To answer your 1st question "Why do Piper not provide ......?"
Because it would require the expense of an extra series of performance flight tests.
Q. What performance figures are prospective customers normally interested in ?
A. What is the shortest strip I can get this plane in and out of ?
25 degrees of flap will reduce the minimum safe rotate speed and will therefore reduce the take off ground roll required. Compared to this the take off distance required with 10 degrees will not make the aircraft a more saleable commodity so it is not deemed to be worth investigating.
Back to the practical reality. The difference in rotate speed between 0 and 25 degrees is, off the top of my head about 10 knots, if that so when would you propose to use 10 degrees ?
If the runway length is too short for comfort on 0 degrees then just use 25. If you can comfortably get off the ground with zero, then using 10 will, contrary to popular belief only serve to degrade your climb rate once airborne.