As a product, the R-D1 has clear signs of being built for technology promotion. I don't think the amazing Seiko dials would have ended up on a regular camera. For most products and without knowing the Epson organization, I would be surprised for these departments to even talk to each other. The camera also came in a box that I recall was nicer than what Leica M8 shipped in.
The rest of the Epson digital camera lineup does not appear very exciting, although there may have been some products that were nice at their time and price point. This was a special product for the company, or a very powerful individual in the company. Which of course does not rule out plans to move some units. Those plans were however not backed up by marketing (at least outside of Japan). Epson is probably not enough of a camera company for that to happen, although this product proves they can make cameras with the best of them.