Not as ergonomic, no e-paper, and not hackable. They're fitness gadgets, not tools.

Certainly.

I think openness is vital for such a (new) platform or ecosystem in general. The ecosystem has certainly gotten older by now, especially compared to when Pebble first started, but in my opinion a lot of the organic growth has been stunted. It's too difficult to try new things, find new useful applications and to innovate with all these walled _wearable_ gardens.

I still miss a few things the Pebble had but my Apple Watch doesn't. Which in turn makes it feel less like a tool and more like a gadget.

I’d strongly disagree with tool vs fitness gadget here. Compare a Garmin to an Apple Watch or pebble, and it absolutely is a tool. Arguably the MIP display beats out the ePaper, ergonomics are great (I can use the buttons even while swimming), and it’s built like a brick. Not knocking the pebble too hard, but it certainly seems like an enthusiasts toy. I’m not sure what else would last me a week while tracking exercising for an hour or two each day.

Is a diving watch a tool or fitness gadget?

I have the opposite opinion on what's a tool and what's a toy.

Garmin devices are hackable to an extent. There is an SDK so you can write custom apps, although some of the hardware functionality isn't accessible.