Lol. That's my thinking, too. But I read about people taking photos and doing barcode scanning with iPad, so apparently there are users who'd like Passbook on iPad, too.
I have watched several "live" events on the tube recently (not going to name them for various reason) but I was surprised to see some Joe standing there taking either a video or photo on an iPad. If you put a camera on a tablet people are going to use it sooner or later. No matter how silly it looks or doubtful we are that folks will use it. I remember this one time I was doing some repairs at home...needed to place something, but didn't know what it was called...grabbed one of my Android tabs (not going to take my iPad out to the hardware store (lol)), took that photo, end up in HD and showed it to one of those experts. That larger screen made the difference, too, because several people ended up looking at it at the same time.
I do barcode scanning for my movie collection...easier to do that on a smaller device, IME. But I do find it harder to tell is a subject is in focus on my phone, but much easier on a tablet.
I look forward to having my "loyalty cards" all in PB. I hate having those in my wallet. This app will be a keeper if folk support it. Seems like some big names are already onboard....Target, Walgreens (these folks have strong app support), and several airlines. Of course, Fandango is there too. Smart.
I think PB will proved to be useful in the not distant future. Apple can make it happen.