Someone else was bothered by that and wrote an app. It's free.
MyDirections. It makes Maps a usable app. (It's like Contacts - you name the location whatever you want and MyDirections finds its lat/lon. Then, when you tap the entry in MyDirections, it runs Maps, telling it to navigate to that location. It's the way Maps should have been written in the first place.)
You'll have to change the settings in MyDirections to default to Navigate and Car, or it defaults to display and walking. (It's in the menu in Settings.)