Why don't Metro apps allow you to zoom in on the content displayed ?

It really ticks me off how both Metro and iOS apps don't allow you to simply press (ctrl +) or do pinch to zoom in order to zoom in on the content in the app. I don't have bad eyesight but I am addicted to this as I constantly do it in the browser and so do a lot of people I would think. Seriously how many of you have found yourselves trying to zoom in on whilst in App ? It should not be hard to do, don't change layout or anything just zoom in on the section required and put the rest past the frames. I really hope this feature will be implemented soon.