Well... My RV-9A suffered corrosive soot incursion from a fire in hangar two down from mine. If it had been primed during construction, damage would have been much less, and cleanup probably lots easier.
Granted, the insurance adjuster works in the humid southeast, but he was emphatic that all planes should be primed. And if you sell your plane to a humid climate, how might that affect resale value?
Just another point to think about... but I'd probably make the same decision as you.
RV-9A at KSAV (Savannah, GA; dual G3X Touch with autopilot, GTN650, GTX330ES, GDL52 ADSB-In)
Previously RV-4, RV-8, RV-8A, AirCam, Cessna 175
ATP CFII PhD, so I have no excuses when I screw up