Great features.
Yeah, I have a number of apps I installed for one-time operations (a number of obscure dev apps come to mind), and I find out that they are still hanging around, like my drunken Uncle Bob, hovering around the keg.
I regularly go through and turn off location tracking on almost all of my apps (or at least turn them to 'while using'). But sometimes I'll have to turn them back to permanent for a specific reason (e.g. sharing my location with someone while I'm coordinating with them). This feature reminds me to turn it back off.
But I also potentially see the need for a feature which allows always-on access for a limited period of time.
I have some apps, i.e. Unifi Protect, that requires access to background location to send activity alerts when nobody is home, and i frequently get alerts that this app has used my location in the background, and despite selecting "allow always" it will pop up again in a couple of weeks.
To further add insult to injury, i appear to have "trained" my wife so well that she defaults to selecting "deny" for apps she doesn't use, and "only when in use" to everything else, which then results in a flurry of motion alerts :)
This might hurt for example Tile. I think their “network effect” is somewhat depending on this kind of background location tracking.
It's a new feature due to the more fine-grained permissions that are allowed now on iOS. It prevents apps that you may have previously allowed location access to (when it was just binary) from adding all these new "features" to use your location in ways that weren't disclosed that way initially.