You know these are favorite topics of mine, so it will be no surprise that I heartily approve, where in Daniela Borgialli’s Tango Workbook she says that her university students are expected to routinely change partners and change roles during classes.
In my mind the time to practice with your regular or preferred or ideal partners is in private practice time or a private lesson. Group class is a way to review and expose yourself to new concepts, new figures, and new partners. If at milongas you never change partners then no one is going to force you to change in class, but if you expect to dance with various people, learn to dance with various people. (Teachers: please do it in a routine, defined way, not haphazardly or at your whim.)
Despite its macho origins, it seems to me that Argentine tango, more so than other bailes de sala, is a wonderfully egalitarian art form. Aside from a few niceties of style and adornments, the whole gamut of tango technique is accessible to and useful to both partners.
You think followers don’t need “intention”? Consider this advice — Make a statement, not a question. FOLLOWER: “Ok, I’m here and I’m on my axis (or on you, if that’s what we’re doing); I’m ready.” NOT, “Um, was this what you had in mind; oops, I’m falling into another step, I hope it’s what you intended?” [Thank you, Arjay Centeno at the 2015 Austin Swing Championships for a funny presentation of this and other good ideas — an example of how dances do have things in common when you get down to basics.)
You think leaders don’t need ochos and molinetes and cruzadas? Even if it is only in an abbreviated form — swiveling your feet to align them properly, stepping molinete fashion around your partner to align with them, crossing to give your partner room for a step — you are doing the same actions.
To open up the full range of possibilities in the dance, both partners need comfortable access to all the tango technique, and more than from just a technique class or class warm up, they want a working knowledge in both roles.
P.S. While looking for an image to illustrate this article I find that Daniel Trenner was advocating for Change Role teaching back in 1998!