That does seem a bit extreme, even to me. The redundancy between the iPod, iPhone and iPod Touch seems a bit strange. I could see the iPod and the iPhone since the iPod offers much more storage for pure music.

For me, my breakdown between iPhone and iPad seems to be for these uses:

iPhone: calls, text messaging, camera, video chat, alarm, instant messaging, podcasts, music, GPS, social checkins, reminders, flight status and boarding pass, some games to pass the time, twitter, maps reference, mail, some web browsing, and calendar reminders/game reminders (cursed Eve)

iPad: Netflix, local LAN video streaming, news video streams, books, comics, mail, web browsing, magazines, star maps, photo browsing, maps for reference, pdf and other documents, longer session games, SSH, VPN access to work, twitter, flipboard for RSS browsing, notes in meetings, remote desktop, video podcasts, a way to show someone at work a site or e-mail to discuss, and battery life. Because it can just sit in standby and receive push messages for so long, it's much easier to use for work e-mail when away then it is to wait on a laptop to boot and sync down messages.

Yes, much of what I do could be done on the iPhone, but it's just not the same. The iPad virtual keyboard is much more usable, and with the higher resolution, SSH sessions and remote desktop sessions are also easier to deal with. Comics and books work better too, since there isn't as much scrolling and squinting. In many ways the iPad has replaced what I'd use a small laptop for. The laptop still is useful for a real keyboard, but I could tote around a bluetooth one (no jailbreaking required) to type longer things on the iPad. A larger laptop still appeals to me for mobile gaming (WoW, Starcraft and such), but only when I live near friends I want to game with in person. For now, the desktop computer fills the roll for big games.