Business does that all the time. I go to a local steak and chop house called Donovan's in La Jolla. I don't go there and ask for a hamburger, because that's not what they offer - what they do have is among the best New York Strip steaks I've ever had, along with other steaks and pork chop plates. Over time, as tastes have shifted, they have offered things they didn't offer in the past. Likewise, if Apple sees that the market simply insists on having 4" or larger smart phone screen sizes, and iPhone sales suffer as a result, they will offer it. Have iPhone sales suffered? I'm not sure, but I think they set another record for quarterly sales of iPhones, but in any case, they are clearly not suffering a loss of sales. They just don't do the "throw everything at the fan and see what sticks" routine that so many other manufacturers do.
Microsoft also restricts access to the phone OS file system. Should they allow it simply because some fraction of percentage of the users want it? Microsoft also didn't allow Flash on their mobile OS -- where was the outrage? We've been down this road before... if you want access to multiple screen sizes, Flash, a common file system, your choice is Android. If you want access to a vast library of music, podcasts, university classes on audio, etc., then Apple is a much better choice -- as long as you can accept the limitations. The advantage Apple has is a coherent method for obtaining and then accessing content on your iOS device, the disadvantage is limited access to the nuts and bolts of iOS. That's by design and you can either live with it or move on with your life.