A machine doesn't listen to itself, does not percieve itself or music, and that's why the music of a machine has no living, breathing, real-time personality. If somebody "plays like a machine" and lacks personality, it is because their ability to listen, hear, percieve, is stunted, at best. Playing like a machine is not truly about lacking flaws. Being human is not truly about having them; it is the ability to percieve.
Karli, I think I understand where you're coming from, much more than where anybody else is coming from on this...but then I've not read most of this thread nor have I the slightest interest in this thread, except to highjack it and use it as a vehicle to promote the incomparable genius of Conlon Nancarrow. I urge you to listen to his Studies for Player Piano, which are living, breathing, and overflowing with joyful and delightful personality. Of course it is Nancorrow himself and his delightfully complex music from which the personality is born, but you can't say the instrument (with his doctoring) is insignificant. In fact it is a major part of the humor, the joy, and the genius of it - Nancarrow chose to write for a machine, pieces impossible for the human, and he spent this opportunity well; he went far enough and beyond to make it well worth it.
(Now that I say this, there are these ambitious few who attempt to tackle aspects of a few of these studies in various ensemble arrangements. You can find a trumpeter and a bassoonist playing along with dead on precision with no. 7, and also a 2 piano arrangement of the same attempted by Thomas Ades and somebody else at a festival!)
Anyway, I read the quoted on a week in which I've been exploring again these player piano studies, listening to the five disk set of all 50 of them on Wergo on my hour long drives into work, and on a day when I shared a listening of two of the disks at the home of a couple singing friends from work (and yes, we all enjoyed it very much). Music for a machine with the personality of a composer, yes…yes indeed.
To blabber on, I was just looking at Ligeti's final etude, "Canons," one of many inspired by musical mechanisms, and Nancarrow specifically. In the instructions concerning the necessity of tempo alterations due to fingerings, he writes "The machine occasionally falters." That's a wit I can appreciate!
In summation, I think Conlon Nancarrow is great,
The end.