Even for signage it has some spectacular failure modes. Where LCD would just not show anything, the e-ink will keep the last (and invalid) information confusing everyone in the process.
Then you are a niche case. In order to forward a new technology, the masses need to adapt it. Apple, for instance, had to upscale the manufacture of Retina displays by starting with a proven successful product - then moving it to the iPad, then moving it to MacBooks.
We had e-book readers for e-ink, but they stayed at a super slow refresh rate. There was no reason to create a tablet sized e-ink display until the ReMarkable removed the issue of the delay.
Now we will have clones of that, and after that we will see a push to larger displays.
Mass manufacturing is hugely about cost balance vs. demand.
I think digital whiteboards in offices would be a great market for this. Again, though, if you’re going to draw on it at all there needs to be zero latency.
>There was no reason to create a tablet sized e-ink display
Of course there was; large-format publications like newspapers, magazines and technical documents. All requiring large display area and not needing fast refresh. But yet, all ignored by the manufacturers and so LCD tablets became the default for those despite their drawbacks.