Bah.
Bah? What are you, Doctor Doom?
The whole point that people are making on this thread is that stereo WASN'T around to the degree that it is now back in 1967, when these records came out. So the artists were recording and mixing their records for mono. So if you have no interest in hearing how the artists thought the music should sound, that's your choice. I'd choose to hear how the band envisioned the album, not some engineer barfing out a stereo mix without any of the principal artists around to supervise.
As for 'using the pieces that were already there', plenty of stuff that is on the mono version of PIPER AT THE GATES OF DAWN got lost in the stereo mix. So you hear elements that fell out of the recording during the transition. The same goes for the mono mix of THE KINKS ARE THE VILLAGE GREEN PRESERVATION SOCIETY - the mono version seems so much livelier than the stereo version.
There's not much separation on contemporary recordings these days anyway - they often end up a thick, compressed wad of mid-range goo. So if you want that, it's all yours.
Tom.