Apple Maps has the same feature, but it's an opt-in change so I just ignore the announcement and it'll keep me on the previous route. Plus it's one of the things Siri works well for, just saying No will cancel it.
This feature is necessary when you're taking a long trip like SF-LA - it calculates the whole route because that's what the user expects, but of course there's no way the LA route made hours ahead of time is going to be the best one, since it doesn't know what traffic is going to be where.
