I don't think it would be a wise idea for Apple to increase the price on the phone just by including things other manufactures already have without a price increase. The HTC M7 for example had a higher resolution, larger screen with a standard for 32gb storage.
Apples prices may become a focal point if they increased them. Then a lot of people would start comparing price more then they already do and start questioning. Lower res screen, still smaller size screen, no NFC, no stereo speakers, relatively small battery, , no wireless charging, no dual antennas for CDMA carriers or SVDO, half the RAM, etc etc all for MORE money. Probably something Apple doesn't need to do.