I think it's because pinch-to-zoom is actually terrible, although it has a cool name and looks cool. The problem is that it requires two points of contact to move apart, and you also have to hold the phone at the same time.
The best way to do it was screw-to-zoom, where you draw a spiral to zoom in or out; righty-tighty to zoom in, lefty-loosey to zoom out. "Screw-to-zoom" is a bit gross for marketing, though. Maybe "spiral-in, spiral-out"?
Requiring it to be usable is terrible. That said if images are important to the content, it's almost impossible without zoom to get a decent experience on a tiny screen.
The best way to do it was screw-to-zoom, where you draw a spiral to zoom in or out; righty-tighty to zoom in, lefty-loosey to zoom out. "Screw-to-zoom" is a bit gross for marketing, though. Maybe "spiral-in, spiral-out"?