Yeah, I think that a smartwatch along the lines that you describe would be a plausible consumer product. For me, limited battery life would be the killer, but that might have solutions. One that I would like to see is ePaper for the display, which would also help with outdoor readability. On a watch, you could experiment with color schemes that are not your Kindle classic black text on white background. With a good designer, an ePaper smartwatch could look a lot like a Swiss fancy watch, but pack all sorts of functionality inside. (I've been convinced for years that the "bigger and fatter" trend in men's watches is a scheme designed to pave the way for wrist computers.)
The Pebble was supposed to have an e-ink screen, but it turns out they're using some type of LCD sort of like your standard digital wrist watch.
I guess the problem with e-ink is that even the fastest displays are too slow for interactive UIs. E-books sort of pull it off since the benefits while reading outweigh the horrible interface responsiveness, but for a smartwatch I think it might not work.
I think a lot will depend on whether they can design a non-obtrusive charging method. My idea is to make a little inductive platform that you keep in your bathroom, which is the resting place for the watch as you shower. When you are done with your shower and put the watch back on, it has a guaranteed week of normal-use battery life. (Not that users would only shower once a week, but sometimes they won't shower at home and they shouldn't have to worry about watch death.)
I don't care much as long as it's easy to plug in and take out, like with an inductive charger, then it should be fine.
A lot of people I don't typically wear their watches at home, and I guess for even those who do, most don't sleep with them on. Especially if it's a heavy piece, as smartwatches will be for the foreseeable future.
For me, dropping the watch in the charging pad next to my bed, or the door won't be a big deal.
In any case I don't see a big difference between needing a charge every 2 days or every 5. You'll be getting into the habit of charging it every night or risk forgetting to do it when the battery is running out.
The most important bit is the battery life. The Pebble is supposed to last 2-5 days and the Samsung Gear will last you a day if you're lucky (but that's a beast of a watch, hardware wise).
Nobody is sharing details on the upcoming Android Wear devices, which is annoying but expected. Hopefully it'll be at least a week, but honestly I'm not too hopeful.