Originally Posted by SolipsismX
You've been having a lot of issues with comprehension lately so I'll try to speak as plainly as possible.
If you increase the display size but keep the resolution the same you are using larger pixels. This means that items on screen will be larger then they would be on the smaller device.
If you go the other way and increase the pixel density but keep the display size the same you are using smaller pixels. This means that items will be smaller if they only matching pixel to pixel.
Perhaps you're not familiar with Apple but they have a very strict dedication and focus to their UIs (that stands for user interfaces), especially on their iDevices. Just as Apple revamped the UI for the iPhone 4 when they quadrupled the number of pixels, even going so far as using a different system font for that phone, they will do the same for the any change in the UI size or resolution for their iDevices.
Vendors using Android OS seem to be perfectly fine with having the on-screen elements be smaller or larger without any consideration for their usability but Apple doesn't do that. You might that a 4.7" iPod Touch would be good enough with the UI from the 3.5" iPod Touch but Apple would want to consider another row of icons, or keeping the same number but making spacing them differently, or adding more controls to apps because there is more screen real estate, or adding a new kind of split view because there almost double the screen area.
It's really that simple.
The problem with your logic is that we're talking a minor change, all things considered. Your logic holds if you are talking about going from a 3.5-inch iPhone to a 9.7-inch iPad but that is not what we're talking about, not even close.
As such, you are quite simply wrong in your contention that a relatively minor increase in screen size would cause all sorts of problems. It is, likewise, unlikely that developers would bother to have two distinct versions of their software, one for the 3.5-inch Touch and another for the 4.7-inch Touch. Instead, the same software would be viable on either version and that would be the end of that. The IOS, meanwhile, would require virtually no adjustment.
Clearly you are confused in that you are taking the process that occurred when the iPad came along and applying it with no real thought to making the Touch screen a little larger. It is not the same thing, not even close.
It may well be that Apple has no interest in increasing the screen size of the Touch or the iPhone. But I doubt the reason for not making such a change would have anything to do with thinking it is too much trouble. The decision would be based on marketing considerations, user experience, etc., not how to make it happen. Making it happen would be a matter of changing the iPod Touch itself. It's not a software matter. That's simply not a factor in this case.
Basically, I can't fathom a software program built for the current iPod Touch looking at all out of place on a slightly larger Touch. It would translate just fine. No reason to think otherwise.