Powdercoating is about the most chemical/abrasion resistant coating you can get.
I should know
I've had to get it off several pieces.
Short of full on Aircraft paint stripper formulated for Poly's you almost can't get it off.
Even if you don't have salt on the roads, unless you live in a very arid (low humidity) environment (like say Tucson, AZ) you will have corrosion.
Almost all places on Earth are now sunjected to industrail polution of one form or another.
Sorry LittleHo, I think perhaps your experience may be a tad limited with regard to paint adhesion.
18 years experience with all types of machinery has proven to me that while a Rattle can paint job can be made to look good, it won't last under use.
Now, if you want to redo it go ahead. If you are inexperienced do a little research. Doing a quality job isn't really rocket science. It just takes a little knowlege and practice.
If you took your car in to have it repaired after an accident would you be happy if they spraved paint over a new metal fender with no primer? I think not.
Would you be happy with rattle can spray paint over a new or repaired metal fender? OF course not.
Sandblasting then forgoing primer because you believe the blasting has magically given the metal adhesive properties? Come on man, All the blasting does is remove the surface coat, contaminates, and rough up the surface.