From what I read some time ago, e-ink displays use almost as much energy as normal displays if the contents change all the time. The one benefit of e-ink is the ability to show static content without using energy.

That is probably another reason that e-ink laptops haven't really become a thing then - practically any use besides maybe basic web browsing and emails would require a decent refresh rate to be reasonable, removing the benefit of using e-ink over the normal display