A bunch of reasons, in no particular order: Having my phone visibly in-use makes it easier to avoid the temptation of touching it. I have a long history of playing video games, and seeing a "mini-map" is just how I'm used to navigating, even when I know the way. Having navigation that incorporates real-time conditions helps me avoid construction, traffic jams, or other miscellaneous issues. I have a pretty bad sense of direction, and it takes multiple trips to internalize routes, which doesn't happen because I drive infrequently (typically less than weekly, because I prefer to take the bus).
I guess it didn't occur to me that people might not remember how to get places in real life.
I don't think I could stand to have any sort of lit-up screen doing something in my eyeline when I'm driving. I turn off the backlight on the dashboard when I'm driving at night because it annoys me.
Again, it's also helpful for warning realtime issues like poor traffic conditions, road obstacles, speed traps, etc.
I don't know why people don't seem to understand what I mean when I say "I don't want any kind of lit-up screen in my field of view for any reason".
Why would I care about speed traps or road obstacles? "Poor traffic conditions" isn't really something I can do much about, either.
The response is to “it didn't occur to me that people might not remember how to get places in real life”, which is a rather limited understanding of why people might use navigation. I am not here to preach to you the benefits of this technology, simply clarifying an additional use case. There’s no need to conflate your own needs or tastes with the rest of the driving populace, either.
Also, those notifications can likely be conveyed using audio-only warnings, anyway. Making all of this discussion a bit moot.
Finally the entire benefit of live navigation is to find alternate routes with less traffic! That is something you could literally do about.
Most of the places I drive, there aren't really any practical alternative routes that don't add several hours and often things like a ferry journey to your trip.
I don't want audio alerts for anything either. It's really simple - I don't want anything in the car that beeps, flashes, lights up, makes noise, or indeed does anything that is not directly part of making the car go in the required direction at the required speed.
Okay, that’s fine for yourself, but as seen in this subthread, other people have different tastes, and needs.