Quickstep,
You are onto something interesting this time.
Generally straight steps are not executed well, because they turn out to be impractical at more than a social-foxtrot type scale of movement!
Pretty much all actual figures in the more dynamic dances incorporate either CBM or a constant side lead. This introduces a diagonal component to the motion, which creates space for both partners to move without obstructing each other.
Now you are quite right to point out that CBM does not mean diverting the track of the foot, but instead rotating the body while sending it and the foot straight. (Last I heard, Jonathan still tends to get that one wrong, and you can see a lot of people who do know better diverting their foot way off the track on step four of a spin turn).
To deal with this practical, I'd make two suggestions:
1) Do not ever dance body square to movement in closed hold. This is fine for walking exercises or arms length hold, but trying to do it in closed hold will cause you to develop bad habits for accomodating and awkward situation which simply does not occur in actual dancing. Instead, dance closed hold actions with the legitimate CBM or side lead which they are designed to employ.
2) Dance the CBM actions with a mind towards common progression. Use the body rotation of CBM to make space for the partner, while staying "in their way" and moving just ahead of them. This creates much more efficient joint movement than falling off to the side on a diverted foot in order to "get out of the way". The backwards/inside partner needs to make space, but they should not make space any "faster" than it is actually needed - no big gaps on the turns please.
Also, something to think about: when viewed with respect to the path of net movement of the fictional "joint center", properly executed turns actually "turn" the opposite of the way in which the are named. For example, 1-3 of a natural turn accomplished a path change of 1/8 turn to the LEFT. If we draw the path of movement on the floor, there will be a vertex at the footprint of the second step. Given that the turn is actually towards the center of the room, there should be no steps falling to the outside of that originally DW line of travel painted on the floor.