Readability

Many, many designers (who "tend to have excellent eyesight" as usability guru Jakob Nielsen says) need to wise up about readability. For example, in my judgment, most web sites have too small text. I have to set up the default size quite a bit in my browsers (incredibly, you still can't change that in Safari on iPad), and even then I often have to enlarge it further on individual sites. And with glasses, my eyesight is not all that bad, probably average. 

Readability of course also includes contrast. See for example this example from iOS 7 on my iPad: 

See the word "downloading" on the right? Nope, me neither, well hardly. 

A similar issue: I have set the text to Bold in Settings, but the icons in iOS 7 are still very small, very low contrast, and very thin-stroked. That's the thing with Apple, mostly they do great, but sometimes they will really let form get the upper hand on function. 

Fortunately, sometimes they fix it later. The last version of iTunes (app on Mac/Windows) had all-grey, low contrast buttons and text, but with the present version it's back to being well visible, colors and better contrast and so on. 

I admit these are not easy things to balance. I've built many web sites, and when designing apps and web sites, one has to account for the whole spectrum of eyesight levels, and often a big spectrum of screen sizes and qualities too. So if you want to keep readability on the big majority of all that, you are very, very restricted as a designer, and I can see how that is frustrating, all your education and inventiveness gone down the sink, or a lot of it anyway.