Electicism – why be surprised?
Various critics over the years have expressed confusion if not discomfort about Herbie Hancock’s eclecticism, genre crossing, movement between playing acoustic piano and using all sorts of musical technologies … but I’ve never understood why anyone should be surprised. Its unfortunate that “purists” in every musical walk of life insist on applying their own biases and aesthetic preferences to what they expect from creative musicians. Hancock’s playing with Miles integrated aspects of his early roots in the pianists of the previous generation (in high school, he listened to Oscar Peterson, Eroll Garner, George Shearing and others) – but also (particular beginning in 1965), the abstraction that dates to his early gigs with Eric Dolphy, the interest of the Miles band in Ornette Coleman (and of course John Coltrane), and during Hancock’s college days, when he was listening to the music of Olivier Messiaen and Igor Stravinsky, later expanding his horizons to Krzysztof Penderecki and others of the European avant-garde. And why would Hancock’s interest in funk and popular music of every era be surprising? The musical style during the early years of his professional life, with Donald Byrd and on his own early 60s recordings, was in the context of the music often referred to as “hard bop.” This was an eclectic music that bridged bebop with gospel and blues; you can hear it all over Hancock’s first recordings under his own name. Hard boppers wanted to continue the advances of Charlie Parker, but in the context of rediscovering the music listened to by people in their neighborhoods. As for electronics, Herbie Hancock not only began college as a major in electrical engineering, but, along with Tony Williams, had as early as 1964 become interested in experimenting with tape and electronic musical devices. And he had been listening to the music of Edgard Varese in college and during the early 60s, Karlheinz Stockhausen. Let’s hear it for eclecticism!
Bob Gluck's Blog 
I don’t mind that he is eclectic — I respect that and am in awe of his talent. What confounds me about Herbie is that he has never, in my opinion, equaled the greatness that he acheived during the 60s with Miles and his own recordings. These days he is practically on his own level as a piasnit. But the subtelty and the touch is missing.
I think that Herbie’s playing with Miles was specifically about touch and harmonic subtlety – particularly with all the fractured chords and clusters – some of the kinds of things that you note. In a sense, the music was very textural, but using the piano and the main vehical for that. The Mwandishi music and much since then has been about different kinds of musical issues; when its been textural, his pallet has been organized around different kinds of instruments or approaches to making music. But there have been exceptions, like his duets with Wayne Shorter around 2000, and his recording of Joni Mitchell songs, where you’ll find his interest returning to those concerns, specifically as a pianist. I think that it is important to not assess anyone’s overall musical output according to particular musical values that may be more relevant to a particular period in that person’s work. Another interest side to this question is about how Herbie plays as an accompanist, where his pianistic gifts really jump off the page. I consider his work with Miles as being very much in that model.