I wouldn't use anything without a mouse and keyboard for 5 hours, much less 10. Free apps in an app store? Shocking! How many of those 70 apps do you use daily, and how many of them are worthless cruft that looked cool before you downloaded it but now that you have you realize it wasn't worth paying for anyway? How about the three you did pay for?
You're right, I haven't used iTunes since the app store was introduced. I thought the app store was just another section of the iTunes marketplace. Either way, I've never seen a reason to have it on my computer, and I wouldn't want to be forced to use it to update or add new content. My Zune has shit like that which is ones of the reasons I use it less than my $20 Sansa.
USB not necessary? I guess not if you're happy with what Apple thinks you need. I could see using a USB port for infrared, external storage, peripherals that don't use Bluetooth, or whatever else.
I don't know why you'd need a keyboard and mouse to read/watch vids/browse web.
free apps used daily:
facebook, aim, weather channel, sportacular, ny times, ap mobile, pandora, i.TV, TUAW, engadget, national football post, streak for the cash, ochocinco
free apps i use when i have a need for them:
shazam, urbanspoon, showtimes, yelp, convertbot, jambase, runkeeper, rotten tomatoes, imdb, webMD, moodagent, flashlight
paid apps:
mlb at bat 2009 - last year's version, used it everyday to listen to or watch baseball games
emergency radio - listen to police scanners from around the country which is very entertaining late at night
fieldrunners - excellent tower defense game
there are more that i would use if i could, but my living situation doesn't allow for private wi-fi networks, so apps like remote and airsharing can't be used. for the examples you list as reasons for a usb, none of them really hold up. i'm assuming you mention infrared for things like home theater control. there are already countless apps to do this via wi-fi. there's not really any reason to ever need to hook it up to an external storage device. all media transfers are done through the 30-pin port on the bottom. if people want a keyboard for it, odds are they are going to buy the keyboard dock or go out and actually purchase a bluetooth keyboard for it. the average consumer doesn't just have keyboards laying around everywhere like the fine folks of tw.