The question in this thread reminded me of my own teacher's views of Hanon and Czerny. I remember taking a czerny exercise to a piano lesson once and my teacher, a Hungarian concert pianist, ousted it immediately, replacing it with a Chopin study.
I tend to agree with him that Hanon and Czerny exercises are not necessary to develop technique, although Czerny is slightly more interesting to play than Hanon. If music by a wide variety of composers of different eras (styles) is studied (Bach, Mozart, Beethoven, Chopin, Liszt, Rachmaninoff, Brahms, Debussy, Ravel, and so on) pretty much, if not all, of the technical development required is easily covered; octaves, thirds, tenths, sixths, large jumps, chromatic scales, broken chords etc, etc. And they provide a lot more interest and fun as well as developing skills in expression and general musicianship at the same time, which I feel Hanon, in particular, lacks. My motto is that if technique has to be studied, which obviously it does, then at least make it enjoyable and valuable and improve your musicianship at the same time.