support.microsoft[.]com/en-us/help/4495263/windows-10-1809-change-in-default-removal-policy-for-external-media
NOW they tell us!
Basically there are 2 modes: Fast Removal & Better Performance. Reading/writing to a USB stick [or drive] is generally much slower than reading/writing to an internal hard drive, so selecting better performance makes sense -- it might be considered a no-brainer. And for years that was Windows default. With win10 1809 that changed, with the default now being Fast Removal.
On the Plus side, just yanking the USB stick, rather than going through the Safely Remove process, isn't likely to cause any problems. The Minus -- reading/writing to USB sticks & drives is slower ... it's not just you becoming more impatient.