The only reason (that I see at the moment anyway) to upgrade to Android Auto and Apple Car play, is to make the car more appealing to future owners, and keep the car as up to date as possible.
I don't see the big issue with the car sat nav, and I like the turn info in the instrument display, that sells it to me. The only thing I miss is house numbers, the Sat Nav just takes you to the street, whereas the Garmin unit in my commercial vehicle will take me to the house number. If I used the car a lot for business visits, that would persuade me to use the mobile sat nav, while on business. I don't know why Toyota had to build their own system, when Garmin or presumably Tom Tom would do that. And updates on a very regular basis.
But I appreciate that not having Android and Apple connectivity, seems more important to some, so welcome the chance to get the upgrade.