I suspect because (some?) computer terminals had the escape key there, e.g. VT-100 http://www.columbia.edu/cu/computinghistory/vt100.html http://www.columbia.ed

I suspect because (some?) computer terminals had the escape key there, e.g. VT-100 http://www.columbia.edu/cu/computinghistory/vt100.html http://www.columbia.edu/cu/computinghistory/vt100.html Contrast this with, say, a typewriter that would have no use for ESC.