First, I think we're generally getting more comfortable bringing expensive electronic devices out with us in public -- laptops, netbooks, smartphones, iPods, iPads, mini DVD players, Kindles, or whatever. Some of these fit in a pocket, but plenty don't. We're still bringing these devices out with us, but putting them in bags and/or keeping them on or around us all the time. At any rate, it's a problem that's broader than just reading machines.

On the other hand, there's definitely more room for quasi-perishable, sub-$100 reading devices -- not literally disposable, but not triggering the same kind of "investment protection" instincts. You could imagine an $85 electronic textbook (not any more expensive than many print textbooks now) that don't do anything but display text and other media -- i.e., no syncing, no wi-fi, no large amounts of rewritable memory -- "just" a book. When you're done with it, you could sell it or give it away used -- if the screen breaks, or it gets lost in a cab, that's too bad, but it's not the end of the world.

You could imagine even cheaper variations on this, with greater tradeoffs -- a book whose memory or screen isn't designed to last very long, maybe. But I think you have to be willing to expect/accept some tradeoffs. These things aren't as expensive as they are for no reason at all.

An MP3 player.    Sure there are the Ipods of the world, but there are also $25 off brand mp3 players out there.  The off brand cheaper version is easier to leave on the table. With an MP3 player, I'd probably throw it in my pocket anyway, since they are so small.  The chioce of the premium will always be there for people to pay if they want it and companies should charge a price that's best for their business.

An outdated laptop.   I might be able to leave an outdated laptop on the coffee shop table because I had depreciated it's value to "this worthless old laptop" even though the pricepoint of the used machine might be a couple hundred bucks.

There's a psychological value assigned beyond the monetary price-point, but that value is at least partially rooted in price.  At some point in the future, the e-reader price and commonality will ease the "investment protection."

Craig Mod wrote a terrific post that relates in part to this problem:

As the publishing industry wobbles and Kindle sales jump, book romanticists cry themselves to sleep. But really, what are we shedding tears over?

We’re losing the throwaway paperback.
The airport paperback.
The beachside paperback.

We’re losing the dredge of the publishing world: disposable books. The book printed without consideration of form or sustainability or longevity. The book produced to be consumed once and then tossed. The book you bin when you’re moving and you need to clean out the closet.

These are the first books to go. And I say it again, good riddance.