Yes, this was a big surprise in iOS 11. I can understand the appeal of making it work this way, but I wish it was implemented as a parallel set of options. Or at least make it configurable in settings of how it should work.

I feel the same way about the "Do Not Disturb While Driving" feature. I like the feature a lot, and I've been using it, but I wish it was a parallel feature as well. My "Do Not Disturb" patterns are different in the car from when I'm not and I'd like to be able to configure it as such.