Yes, NEX cameras are good for street photography. Why? It is small, really small if mounted with a small lens. It looks like a point and shoot camera, so people around you do not take you seriously offensive or intervening. NEX has good sensors. NEX is usable for hip shots too! NEX can take almost all lenses of the world (with proper adapters of course). I have a NEX 3 and two PENTAX lenses(30mm f2.8 and 50mm f2) and a Jupiter 9 85mmf2 and one 18-55 Sony kit lens and a 16mm f2.8 prime of Sony.
For us who walk life with photons and frames and compositions....and creativity.