I'm assuming if you didn't have to accept immediately that you could push it off until you have time to do so. In addition just knowing that there is an update is a boon on it's own. If I know that the code has changed on my car and something starts acting funny, I'm a lot more likely to suspect the software and report issues properly than if it stealth changes it (I would assume mechanical wear and tear at that point).

I don't have an updatable car. But I have used Windows. And it's become my practice to hold off for a few days after updates come out, and check for horror stories. And I typically do a manual backup before updating.