I do not think that satnavs change our brains.
The satnavs just become more common and more powerful. They can store map details that were not available when those things first hit the market. Additionally people have more trust in computers and software (I am a software engineer, so I don´t). That leads to a situation where more people get the chance to get in trouble by using stanavs. There may also be a survivor bias. We wont hear much about those people who realized on time that the satnav may have plotted a route that is less desireable. Most humans tend to follow the directions of a perceived authority. That would explain the people´s willingness to just follow the satnav.
When I bought my last satnav, I spent some time to configure it to not use dirt roads I would not consider fit to use. I realized that the default configuration would use such roads only after the device tried to plot a route I could not follow through (I knew that, so no damage done). The satnav tried get me back on that dirty road for quite a bit of distance and suggested U-turns on every opportunity. Before that I was not aware that the device would do that.