One of the aims of dynamic icons is to avoid having to actually tap on them, if the required information is simple enough to be displayable in the icon itself (e.g. weather, stock). Apps that want to encourage launch could modify just half the icon, or a quarter, or none.
After reading the article, the last thing I wanted was dynamic icons. But your take on it makes sense.
I don't want 'photos' to show me the latest photo I took as that could have been days ago and now finding the photos app is really difficult.
But if just part of the icon changed to indicate something, like your stock folio position (without the red/green background idea) then it works both ways. The icon always looks generally the same - it's a graph - but it changes to indicate some data point that may save opening the app.
That said, how would the icons update if you don't open the app. Each app's developer would either have to send out an icon update notification or would have to provide some level of running the app on a regular basis to regenerate the icon.
I guess apps would have to provide a static function that returns an updated icon, which iOS would call every X minutes/hours. I don't think it'd be hard for developers, it's Apple who would have to do most of the job.
Ah, that is a good point. Retaining a significant amount of the original design probably goes a long way towards keeping the icon quickly-recognizable.
