As you may have noticed, clicking "Upgrade Now" e.g. here, in the "Ready for the Next Level?" chapter, takes you to the page that shows the same pricing. SCS had a different pricing policy regarding upgrades from the MS versions.
Perhaps it's an encouragement to move up to Pro. Then if you want to keep Pro up to date you do so. There wouldn't be much point in dropping back to Studio in order to get the same update offer?