They aren't close to reaching diminishing returns on thinness yet. When I can put a tablet PC in folder alongside paper, each about equal thickness, then we talk about it being too thin.
Paper is thin so you fit many sheets into a small amount of space. I don't see there being a use case for stacking 200 tablets into a briefcase.
Getting it thin as paper is pointless unless your point is to be able to roll it up like paper.
Honestly, we must have different anatomy.
Did you not evolve?
I just picked up a sheet of paper and my thumb turned over. Furthermore the way you hold the tablet with one hand is with four fingers in the back, not just the index finger.
When you pick up a piece of paper, you're not trying to avoid touching a certain part of it, are you?
Try holding up a piece of paper deep in your palm with your fingers fanned out underneath it with your thumb anchoring it near the EDGE of the paper (i.e. as if to avoid touching the screen on a tablet). You're essentially pinching it with the SIDE of your thumb up against the base of your index finger OR you have to bend your thumb down in an awkward way.
Now do this with a paperback book. You can hold it deep in your palm, but because it's thicker you can wrap your thumb over the top and anchor the book more with the pad of your thumb. This is far more stable and more comfortable.
Now do this with a cardboard box that's about 2" thick. You can anchor it on the corner along the top surface with the top pad of your thumb. This is even more stable and comfortable IMO.
Given the fact that of the 30+ million iPads used I've heard this "it's too thin to hold" argument surprisingly infrequently leads me to believe its less of an issue for the general population than you might conclude.
People that drink the Kool-Aid tend to not complain about the flavor.
Easy to guarantee because MS doesn't ship tablets. But their partners do. And I hope they don't ship things that look like the Touchpad. Again, they really should look at the iPad2 and say, "That's the ugliest device that we'll ever ship". The iPad2 should be the baseline for the lowend device. Unfortunately these little previews that show off features like "BluRay support" or "removable batteries" make me fear that their partners still don't get it.
Then why did you bother saying this?
MS can't ship Touchpad size/weight tablets though with Win8 and expect much in the way of sales.