Most of the weight is due to the toughened design, not the battery, actually. We are talking about laptops you can use as a weapon to bludgeon someone, then take with you to swim, and they'd still be in a working state.

Actually you can run over them with an SUV and they still work!

https://www.youtube.com/watch?v=41lXVKSTOGQ

Of course, unlike common laptops, they don't need a case or anything. Just carry them as is with their built-in handle.

If they didn't cost so much I would consider buying one. The added weight may make them slightly less comfortable in one way, but in another way, if you think about it, they're not flimsy pieces of denting aluminum you always have to treat with care, put in protective bags during transport and the like. Using a laptop like this must feel.. liberating.