I'm 53, and I've been very near-sighted since I was a teenager, and have had presbyopia since 40. I need glasses for anything farther from my face than a computer screen, but I don't wear glasses to read books, iPads, etc. I can read tiny text on my iPhone 4 without glasses, and I can make out the pixels on the Retina display if I hold it close enough. While my eyesight might be "perfect" at that distance, I don't enjoy reading books on my iPhone, because my eyes start to feel strained after a while. People are different, so it makes perfect sense that some people would experience eyestrain from reading on the iPad Mini, even if their vision is ostensibly 20/20. They aren't deluded or "wrong."
FWIW, I decided to upgrade from my iPad 1 a couple weeks ago. While the iPad Mini was very nice, and while the screen was as legible to me as that of my iPad 1, the iPad 4's Retina screen was so much nicer. I don't find the full-size iPad too big or heavy, so I bought an iPad 4. It's great not having to zoom in on tiny text, which I had to do on my iPad 1.
So buy whatever works best for you, and ignore the people who tell you you're wrong, crazy, or a troll because they perceive things differently and assume the rest of humanity must be the same as they are.