I'm going to be unpopular and disagree. The book exists irrespective of the physical media, and dead tree format has few advantages. I can appreciate a lovingly-made physical book as much as anyone, but for actual use I don't see why you'd want to be constrained to someone else's choice of typeface, colours,
Maybe the design's part of the experience of the book. Maybe the illustrations are one of the things that give it value and they're better in colour than in a Kindle's monochrome. Maybe there's a map or a diagram to fold out, that you can spread out on a table or desk and get both the detail you need and the overall picture simultaneously.
In any case, depending on the device you've chosen, you're constrained by the fonts built into your e-reader. Sure, you can blow them up, but it's rare for me to find a printed volume difficult to read whereas I find a fair number of onscreen fonts irritating.
and the unwieldy ergonomics[1]
Six and two threes - I don't mind reading a book book in bed. And for reference purposes, I find it a damn sight easier to flick between pages 93 and 393 if I've got a post-it flapping out of them rather than having to click from one to another. This is even more true if it's different books, and I want to compare two or three or four statements simultaneously.
and forward planning[2] that come from such a low bit density.
I'll give you that one, no question ...
If it's anything but a linear novel, the random access of electronic formats wins hands down (I'm biased here, due to my mysterious inability to look things up alphabetically at any kind of speed).
Depends. I'm quite happy with a manual alphabetical lookup, so a dictionary's no problem, but electronic indexing coupled with full-text search wins hands-down. Click to follow a cross-reference - that's good too, and I wasted far too much time with the OED when I had an electromagic copy of it, back when the web was young (and before the thing was available online).
But serendipitous random access? Look something up, spot something interesting on the other page, follow that thread for half an hour - I can do that electronically, but I enjoy it more on paper, and the paths you follow will be different.
And yes, keeping your book collection on spinning rust and/or flash memory gives you so much more space for storing bikes.
It also means N+1 isn't quite as visible when it's got a little out of hand.