Nope, my situation has never been one where a portable would have been beneficial, that is, I rarely have situations where I want to game but don't have access to my console. When I travel, I do take my vita, but even then I don't find much time to play...vacations for me are not just vacations to get away from work.
My Vita was my first portable, and I play it on rare occassion. I don't even game much on my phone. I've sparingly played a couple of mobile apps for my console games (such as the Knack app, or AC Unity app), and that's about it. 99.9% of the time, when I have time and want to game, I have access to my consoles and prefer them over a portable.
Nevermind the fact that my big meaty hands don't work well on portables, especially portables with poor user input implementations and ergonomic designs like the Vita.
Edit: Regarding eye sight, I don't need reading glasses (yet), but at our age, some of us already do and some of us will soon, it's just nature taking its course. Whether that will help with a portable, I can't say myself.
Personally, I have a condition known as keratoconus in both eyes, more severe in the right eye, with the situation worsened by a case of dry eye in the right eye also. Keratoconus is where the cornea weakens, resulting in a bulge in the eyeball. In the case of my right eye, it's off-center and severe enough that vision can't be corrected with glasses or soft contact lenses. Hard lenses must be used instead. The next stage of correction being a corneal transplant. Right now I piggy back hard lenses on top of soft lenses for comfort, because without the soft lenses underneath, the dry eye issue often results in the hard lens catching when I blink and gouging into the cornea. But I digress...
The lenses I wear, because the bulge in the right eye being off-center and pushing the contacts off-center, typically results in a slight halo effect in vision. So it doesn't really matter if I'm on portable or console, it's an issue I just have to deal with right now, and I'm so used to it that I often don't even realize I'm dealing with it unless it gets so bad that it blurs my vision and I realize I need to put eye drops in or blink and push the lenses back to center.