Sony's choice of which albums would get the surround treatment was apparently determined more by force of circumstance than by consideration of which would benefit most. Where the original stereo master was too worn to use they were compelled to locate and prepare for use the original four-track studio tapes in order to have a new stereo mix made; so it was relatively economical to have a 5.1 mix made from the multi-tracks while they were at it.
The outcome of this expediency is that the one-man-and-his-guitar Another Side got a surround mix while Highway 61 Revisted, with its full electric band, didn't. This is doubly irksome as it means that of the three great electric albums two have excellent new 5.1 and stereo mixes, while the one in the middle is only a remaster of the second-rate 1965 stereo mix.