I like doing the half versions too: only the left side of the embrace, and only the right side of the embrace. I think it helps diagnose where and how we actually use arms. While i tend to claim that in close embrace the arms are mostly decoration and not "load bearing" i think that in practice they help a lot to make the dance smoother and nicer and to recover from problems. Other exercises are having only the leader use the embrace, or only the follower use a embrace - homer called this the "little teapot exercise" because the non-embracing person basically does the teapot thing from the song.
I used to be somewhat purist about not using the arms too, and it's a good thing for dancing in CE to spend time early on practicing without arms in order to clean out bad habits and unnecessary muscle activations, but there are a few areas where using the arms a bit definitely makes things smoother with the #1 probably being follower back sacadas.
