Maybe that was it, we don't know. But we do know that wasn't part of Apple's pitch. iPad wasn't pitched to solve any problems - it was just pitched as being better at a list of tasks than either the iPhone or the MacBook (and I'd say the 1st generation iPad being technically better at anything than a MacBook is a debatable topic).
I know that we don't know. You asked me to speculate, so I did.
I do remember the iPad being pitched as an alternative to netbooks. Jobs, or whoever presented at that keynote segment, talked about how netbooks have small keyboards, small difficult to use trackpads, and required being hunched over one's lap to use. I think my problem statement was broad-enough to encompass those notions.
The reason I used the iPad as an example is because the farther out we get from the iPhone, the more difficult it is to justify device's existence. The iPhone can do so many things that what we're left with afterward are just devices on either side that do certain things better than the iPhone - but nothing the iPhone can't also do.
The trend in the last decade has been to converged devices - where everything that used to be specialized to a particular purpose is now either become a general-purpose device, or has been absorbed into a general purpose device. However, somethings cannot become generalized - size of device, weight of device, portability of device. Which brings to my next point...
It's not about screen size; it's about possibilities that open up for a wearable device that aren't possible (or aren't as good) with any non-wearable.
It's not about screen sizes, but it is helpful to view these as distinct categories to see how they fit together and how they fit into someone's life. The way I described is how the consumer electronics industry views converged devices. Talk to any executive in this business at a trade show, and they speak in these categories (not necessarily those exact words, but some variant of them). Actual screen size doesn't matter, but a big screen viewed from far away device is a fundamentally different category than a medium screen device. Doesn't matter if the former is a 36" 720p TV, or a 75" 4k TV, they both occupy the same general category and they all compete with each other at the point of purchase. Most people wouldn't buy two TVs for the living room, or two TVs for the bedroom, while walking around Best Buy looking for a TV for the living room or bedroom or whatever. Same with medium-screen devices - doesn't matter if its a 7" kindle fire or a 10" ipad, they are a fundamental category and they compete with eachother, most people wouldn't use both at the same time or in the same place, or buy both when they want a tablet. Same with the other categories (big screen close up, and small screen). But devices do not generally compete across category lines - people generally don't walk into a Best Buy looking for a living room TV, and decide to instead get a tablet. They might walk in looking for a TV and get both a TV and a tablet - that also shows the two don't compete. They might get a tablet only that day, but they won't suddenly decide they don't want a living room tv. Etc. Exceptions exist of course.
This is all a long way of pointing out that the smartwatch is a new category. Does this new category solve a problem? Apple, Samsung, LG, etc. make it clear they don't want people to choose between getting a smartwatch and a smartphone, or between getting a smartwatch and a tablet. They want you to own at least one product in each category, maybe two in some categories that aren't as portable. After they made a sale in each category, the goal is to get you back in a short time later to upgrade to the latest version in that category - and have brand loyalty so you upgrade within the brand.
I agree that some things might be better on a wearable, no doubt about that. The question is, why should the category exist? Are consumers willing to accept a 5th distinct category, which is not a convergence of previously existing specialized products. The smartwatch doesn't actually simplify anything - rather it seems to just add complexity. Sure it does some things better, but are those things that bad where people will accept a 5th device just to fix them?
