Is design resolution the actual issue though? Many of the questions raised are generally about how to support different aspect ratios, filling the entire screen (to avoid black bars), and to avoid scaling the textures so things look as they should.
Design resolution itself seems to be mixed with those other aspects, so it confuses things. Design resolution should be thought of as a stage, similar to what you would have in Adobe Photoshop and Flash etc. The placement of all the on-screen objects are based off that resolution, and that’s pretty much it.
The real problem is when questions come up regarding supporting multiple aspect ratios, and which of the resolution policies to use. That’s actually the most confusing area. Sure, it may seem simple, in that it requires simple math, but in reality it’s not. It’s knowing what numbers to use in order to make sure everything is still positioned on the screen correctly, that’s the tough part.
Perhaps examples could be provided for each of the resolution policies, so at least the developers would get an idea on when and how to use them.
In addition to that, there’s the setContentScaleFactor(…) call, which adds yet another layer of confusion, and may impact the visuals of the application differently depending on which resolution policy is chosen. It’s the main reason I personally always have it set to 1.0, and just use FIXED_HEIGHT and FIXED_WIDTH depending on device aspect ratio, as I’ve explained in the answer here: multiresolution