Simple, standard user interfaces aren't just for old geezers. They're for anybody who is more interested in getting the work done than in playing with the gadget.
Does anybody remember word processing in, say, 1985? Absolutely hundreds of function key and Ctrl/Alt key combinations to remember! Charts all over the keyboard ... Cell phones are going through that stage of existence right now.
And another thing today's cell phones have in common with 1980s word processors is that they're driven by "creeping featurism." They're bought by people who don't have any experience using them, based on lists of features. "Does Word Perfect have a key to underline a superscript? No? Then we'll buy its competitor, which has 500 features instead of 490..."
Consider cameras, too. All digital cameras today have essentially the same UI. It wasn't always so. Hand a Nikon F3 to an experienced Olympus or Minolta user and he'll only recognize about two thirds of the controls.