re: Guitarists, check out this old box

You are correct. World War II put an incredible demand and subsequent heavy harvesting on Adirondack spruce, which was used for aircraft parts like propellers. It was the top of choice by Martin prior to the war. Sitka spruce is more common today. Not bad but not the same. On that note, Brazilian rosewood (sides, back, fingerboard) is in the same category as ivory and can only be re-purposed, not harvested, so it is also not as obtainable as it used to be. Then you mix in old-growth woods from the mid 20th Century versus new growth wood that is prominent today, mix in changes in design and construction techniques over the decades, and oh yeah, the idea that those pre-war guitars are all over 70 years old and have well seasoned, stabilized and crystalized cell structures ... there are simply A LOT of individual and complimentary contributing factors. And you can't ignore the hype and marketing of "pre-war" just like you can't ignore "pre-CBS" as it pertains to Fender, "McCarty-era" as it pertains to Gibson, etc. It's Marketing 101.