Imacs vs. mac mini and mac pro

Hello, I have posted about my 21.5" imac resolution and text being super tiny, 2 pt. on allot of web pages.
I have a g5 17" imac that I run out the native resolution and it looks fine, nice and clear.
My question is why can I run the 17" g5 out of native reolution and looks good and not the newer 21.5"?
Is it the screen size? or the older processor?
I was looking at a mac mini or an older imac and selling this new one, I am worried that the resolution will be too small on the other computer as well.
Any help or guidance would be great.
Thanks to all.

The native resolution of the 21.5" iMac is higher than that of your 17" G5 which means the on screen text, icons, etc, will naturally be smaller. If you lower the resolution of your 21.5" iMac that will make everything seem larger, however, it will also cause distortion and poor images.

Many folks have difficulty with viewing the newer higher resolution displays perhaps because of poor eyesight or age. There is really no way to lower the resolution and at the same time maintain clarity. You can turn on the zoom feature if you wish but that may not be satisfactory for viewing things like videos.