Here's the full list of what was changed in the first 38 volumes between 1959 and 1973:
Of course, pointing to something happening in the past doesn't mean it's right or wrong. But it does provide some context to those who think this is some new phenomenon being pushed by "generation snowflake" or whatever.• Shorter books (180 pages instead of 225, 20 chapters instead of 25)
• Streamlined writing style (sometimes at the cost of humor, charm, and believability!)
• Elimination of racial stereotypes (for the most part)
• Modernization (no more roadsters and automats)
• Consistency of premises (Frank and Joe no longer gradually age from 15/16 to 17/18)
• Consistency of interior layout (the same typeface is used in all revised books)
• Newfound respect for officers of the law
• Deflation of Aunt Gertrude's character