Either there’s a conspiracy or I am doing something wrong. Here’s a picture of two phones I have, one is for the landline (yes! I still use it :p), another is the cell. Both have screens and both have to be held with the screen facing the ear when talking. And I may be a dirty hippy and all, but I have to clean the screens regularly because the skin on my ear is, well, naturally oily.
I believe this is a design failure more than anything else. If the flip phones pretty much have to have this layout, the type of phones pictured above could easily have screen and keyboard on one side, speaker and microphone on the other side. Granted, the screen would get dirty off the hands, but I do wash hands more regularly than ears!
And really, if there is some unknown-to-me rationale to have the screen and the speaker on one side of the phone, why not have two speakers and two microphones, on both sides. The wonders of modern digital signal processing would easily allow switching off the speaker and microphone on the outer side, depending on which microphone is used.