Re: Not adding up
Secondly lifespan. The cells I looked at all seem to be rated at about 500 cycles, to get 10 years or more use out of them you need to be quite conservative over your use and underrate the capacity (use at least 6 or 7 of them). Thirdly weight. They were over 25kg each, by the time you get 6 strapped together that's going to need some fairly hefty brackets to hold them on the wall.
I think you're right about lifespan. The high quality lead/acid batteries for this kind of thing are much more expensive - presumably for a reason. That said, I've heard people say they get many years out of these when used for trolling motors or running utilities in their motor home. In my case it's going to be a floater so I'm expecting a very long lifetime. This is of course a different use than daily discharge.
Regarding your other comments. I don't seen any need to cover batteries up since I'd be proud to show them off. A closed box is not needed. And putting them on the wall is an odd place to my way of thinking. Regular metal shelving will take that kind of weight, it's no more than storing engine blocks or transmissions.
Anyway, I'm just curious about what the real advantages of these Powerwalls are. Personal preference is certainly legit, but I'm not getting the rest of it. I note too that it is apparently not currently feasible to recycle lithium-ion batteries. Where these batteries may shine is in longevity though. We'll see.