Despite all of efforts in the wrist space, the Pebble is the best in my mind. Why do you want a stylus? Who would type emails on their wrist? My Pebble kicks butt as it reduces the needs I have for my phone, just as the smartphone and tablet reduced the need to find a desktop, but didn't replace them.
All you need do is standardize android phones to have a secondary screen on the other side that never turns off or needs to be unlocked, eink or whatever. Then transition that small screen to also display on your wrist.
I suppose they could even support the "small secondary screen" interface on phones without a physical secondary screen, by simply displaying its contents inside the lock screen.
I used to have a foldable phone with a small secondary screen like that as well; it really was nice, and would be even better if it didn't need a button-press to activate (e-ink or whatever), as turning on the screen is always about 80% of the effort when I just want to see the time... [they can't make the button too easy to press after all, to avoid accidental activations...]
Of course there are plenty of downsides. Constantly glancing at your watch is just as rude if not worse than looking at your smartphone in a meeting, conversation, etc. As you mentioned, there is the high cost for a fairly dumb device. Charging it. And depending on the person, every notification is wedged that much further in to your daily life which is probably not for everybody.
I'm not sure there is a lot of value in a super interactive smart watch that allows you to write texts, make calls and take pictures. The interface seems to be small enough that it's kind of prohibitive among other things. But as a read-only satellite device that displays information from a smartphone/tablet/etc, a smart watch can definitely be a thing.