But even with page numbers on an e-reader, you still have to go out of your way to look to see how many pages there are. With a paper book, you can't help but know where you are.
The progress bar works pretty well for me.
The e-books I buy directly from Amazon now have actual page numbers*. If I press the menu button it gives me an actual count instead instead of a % - "Page 372 of 525." (I've got no idea what "locations" are.)
* I suspect this might not have always been the case. Amazon goes out of it's way on it's newer releases to tout them as "having real page numbers" as if this is a newish thing.