As with all things in life, this is a tradeoff. I'm willing to concede decreasing purchasing power in exchange for some other advantage. Like I'm willing to exchange shitty battery life for a better and faster web browsing experience on my phone, or how I'm willing to exchange years off my life for some added pleasures like cigarettes and alcohol.
That may be, but that's something everyone should get to choose for themselves. In today's world, we don't, and that's wrong.
Besides, we're not even getting any advantages "in exchange" for losing our purchasing power to the machinations of governments and central banks everywhere. We're just getting milked and fleeced six ways from Sunday all the time.
If we could, we'd choose a sound currency, and then our purchasing power would keep increasing steadily (because of productivity improvements and wealth accumulating over time).