As a person with a somewhat unusual fondness for measuring and modelling my own behavior I should be a happy buyer of gadgets for collecting data about myself and my environment. Yet so far I bought none, because they don’t seem to work well without (occasional) data sync with producer’s servers.
I really shouldn’t have to explain privacy standpoint of this. Describing my life and immediate environment in detail to a bunch of people I have never met, some of whom don’t even work for the company yet and trusting all of them that they will not compromise it for as long as they will keep it is to me self-evidently moronic.
But I also avoid such hardware even when data in question might not be particularly sensitive. If I am paying for something to be manufactured, then I expect to own it. If a gadget depends on an external service to be useful, then I am really only leasing it. Services disappear for many reasons and it doesn’t make much sense to rely on their availability unless you can host them yourself. I loath ads, but paying for a service is not a guarantee for its continuing presence either.
I am not against functionality that reasonably requires at least occasional connection to grid. Most social features probably do. Products like phones don’t even make sense without network. Web interfaces certainly do make these devices cheaper and more quickly evolving. So there are certainly good reasons beyond roping you in to make them partially off-loaded on web.
However I don’t want to use those features and I certainly don’t want to give up data I care about for features I don’t. What I expect from devices I buy is my control of data and purchased functionality without others meddling or peeking over my shoulders.