Should I say calculators are useless or stupid, just because I don't need them for that use case?
Your comparison of the calculator and the Google gadget is flawed, as one is made for a specific purpose (calculator) and the other have additional benefits (which I hope work out for those in needed of them). It would be more prudent to compare the calculators additional purposes. For instance the calculator can be used as a dildo, but like the Google gadget, doing so in public will make you look like a freak.
The problem is not the gadget in itself, but the way it works and who controls the data, and how it affects everybody around the user whether they like it or not. It is an invasion of peoples lives on a massive scale.