Well, there is a middle ground between completely unrepairable and completely lego like. Nobody needs to glue the keyboard to the battery and the speakers in a laptop. My laptop is fine. Changing the battery is especially common, they wear fast. And Apple has shown that it did glue an unreliable keyboard to components that didn't need to be thrown away.
As for tablets, you can change the screen or the battery on an iPad 2 for instance - though not easily -, and its form factor was perfectly fine. A bit thicker would not make it horrible so I am sure it is also possible to design a repairable tablet and I think Fairphone proved that it is possible for phones too (although the Fairphone seems a bit thick, granted).
As for smartwatches, I'd argue that while there are valid use cases for them, most people certainly don't need them, so it should not be a big concern. Almost everybody has a phone now, and people who really want to wear the time on their arm can get a regular watch that will last decades instead of a smartwatch. We don't need to carry two computers 24-7. I hope this market is niche and remains niche. But I certainly can imagine that you don't need to glue the battery to the screen in a smartwatch neither anyway.