If it was only that simple. The real problem comes when you have an integrated device like a smartwatch that needs, say, a phone to effectively operate. You may not be able to run the same software you had two years ago: the OS on your phone may require you to run a particular version of, say, the "Phone" app that's been pushed to your device by the carrier and now your watch doesn't vibrate when you get a call.
So, the complaint that this bullshit needs to stop is valid. People aren't going to spend $200 on a watch very often to have it not work, and eventually some form of software rot will make it "not work" because it will require legacy applications to support the watch that aren't available or can't run.
For the record, Samsung's support of the Gear Live has been outright atrocious, so I'm not surprised that my Gear Live will be facing a time very soon where I have to replace it, not because the hardware is broken but because it has simply been stated obsolete. Fuck that, I'll go back to wearing a $10 Casio.