Because we don't see the same in iPhone and iPod Touch forums, both of which have much smaller screens. Conceptually, people should be getting even more eye strain & headaches with those devices but we don't see that. It seems to be a problem uniquely associated with iPad Mini.
The rationalizing seems to go: "it gives me eye strain... so I'm getting a 'Maxi' instead." Nothing wrong with doing whatever people like. I simply find it funny that we're not also seeing: "iPhone gives me eye strain... so I'm getting a "Mini" or "Maxi" too. No such threads. Apparently, things are fine in the smaller screen iPhone/Touch and fine at the iPad "Maxi" screen sizes... just a problem at this Mini size.
And for every post here about eye strain/headaches, there seems to be many more posts talking about how great the screen is... no headaches/eye strain at all in other threads.
Again, I'm in with the wishing that it launched with a higher resolution screen. I just find this funny against the backdrop of apparently no eye strain/headaches/"fuzzy" with the smaller iDevices, etc. Of course, people should get whatever makes them happy.