Probably the best example I can think of is Diane Duane reworking her Wizards series to make it modern-day, but there are others, including owners of a literary estate altering books left to them to make them compatible with current standards.
What do you think? Does it matter if it’s the original author or an inheritor?
If it’s making adjustments here and there to fix errors and/or improve continuity I guess I’m okay with it. Beyond that it’s a slippery slope. For example I’m fine with Stephen King restoring some material cut from his manuscript for The Stand, but the half-assed update to 1990 wasn’t needed.
As for the author or anyone else altering books to appease modern/liberal/conservative/religious/Martian sensibilities, I’m against it.