When negotiators are on the receiving end of a proposal, they frequently choose not to discuss the undesirable features of the argument, but rather to discuss the attractive features of the offer?

This is a true statement. This is a way of making the proposal seem like an overall positive, instead of looking at the ways in which they may have lost out in the deal. Ignoring the negatives is one way of downplaying the situation as well as rationalizing why the overall negotiation was positive.