The Nexus 4 is just like a iPhone, isn't it? Same thing (a smartphone) to do the same thing (make calls, send messages, run apps), but working in a different way. GIMP is not (and has never tried to be) a drop-in replacement for Photoshop, which is why some of the people who have invested (in time, money and experience) in Photoshop struggle to get to grips with it. And yes, Photoshop can do some things that GIMP can't, but if people are taught skills, rather than trained in the use of a particular piece of software, then their knowledge is more transferrable, and as these missing features are added and matured, people gain a very valuable thing indeed: choice.