The sensors should store the information inside themselves and then sync with the mobile when I open the app. No need to have my mobile awake all the time for something like that.

Most sensors do tend to store data for backfill upon reconnect the designers are not idiots and have spent a much longer time thinking about this. Off the top of my head, I can immediately think of several reasons you need to pull the data off regularly:

- Data is needed for real time alerting features for the user (e.g. low blood glucose).

- Data needs to be uploaded to cloud services in real time so carers have access to that data so they can also be alerted.

Both of these requirements require timely access to data. A delay can mean the difference between no real impact and "this user is now in hospital".

I find it interesting how you can't expand your horizon to see that these features are useful to somebody that's not you.

'should'

Someone should redesign them, someone should rewrite OS support for them, and someone should pay for all that?

No, they should've designed it correctly in the first place.