Actually, it is. I don't really need a phone, I just got one because my work offered to pay for it, but before that, I was perfectly content with an iPod touch. The pocketability of iPhone / iPod touch is extremely convenient, but if I could only have one, I think I'd definitely go with the iPad -- as long as it was the one with the cellular connection, that is! Oh, and maybe that's another difference? I've always gotten my iPads with cellular connection, and it is the first always-connected to Internet device I owned. So that's why it's always been more than a toy to me. Where my laptop and iPod touch were both dead to the world while on the go, the iPad was always connected. To me, the iPhone is more a smaller iPad, than the other way around.
That's certainly valid, and I've toyed with the idea of doing something similar--perhaps ditch the smartphone for a dumb phone and carry a cell-connected tablet instead. I know that this is a setup that works nicely for some people.
For me personally though, I don't think I could make it work. My situation is kind of the opposite of your's
A smartphone was my first always-connected device and always-connected iPads didn't come around until years later.
Here's why I don't think it would work for me. I'm accustomed to having that always-connected device fit in my pocket, since before the original iPhone was even a thing. We bring these highly personal devices into our lives and they
become parts of us, like watches, eye glasses, etc. So in this way my phone is almost inextricably linked to me.
So I love the idea of getting my smartphone experience on a larger screen and ditching the smartphone for a dumb phone, but here's the problem. I can't shove an iPad in my pocket. In fact, the size of it really necessitates a small backpack, bag, briefcase, etc. to transport it.
I simply cannot carry something like that 100% of the time the way my smartphone is with me 100% of the time. And I know I'd end up feeling naked if I went out with the dumb phone and left the always-connected tablet at home.
So personally I think I disagree that smartphones and tablets can be folded into the same category. Yes, they share multitouch as their input method and yes they share similar features and uses, but the smartphone is a device from a different league. It's a proven, powerful, stand-alone personal pocket computer and communicator that's always in my pocket.
From this perspective you can see how the iPad becomes a fairly superfluous device. From your perspective, would it be fair to say that your iPhone is that superfluous device rather than the iPad?