Yes, the idea of stereo bleed is to simulate the experience of speaker listening on headphones.
It does more than just bleed the channels, it also rolls off the frequency of the bled part of the signal, and delays it slightly to simulate the time the wave should have taken to reach the opposite ear.
The option to "do it for all songs" was discussed on the alpha team mailing list already. The consensus was that it should get implemented as a tri-state from the player's front panel (All on, tagged songs only, all off).
Hey, empeg guys, is there room in flash to store that tri-state separately for home and car?