A320 Pressurization 'peaks' cause damage to body? (packless tkof)
I'm guessing here but presumably packs off all the time is aimed at increasing the flex temp and hence the engine life. Perhaps there is a power by the hour maintenance contract that takes into account the flex used in the pricing structure.
Since the aircraft was not really designed to operate that way on a regular basis it's entirely possible more strain may be put on the components within the pressurisation/ air conditioning system over time, so it could end up being a false economy. By then though whoever thought up this SOP will have collected their bonus.
It's undoubtedly irritating but the pressure changes are relatively small and few flyers of unpressurised aircraft, including high performance ones have suffered any ill effects, so I think it unlikely you will.