Some people are afraid to really think about the weaknesses of the other sides best outside alternative, or their batna. If i come in and i don't leave self room to concede, i'm negotiating right around my own bottom line. You do want to have lots of issues on the table so that you can create a rational for concessions that you make. It's not just one issue of salary. If i avoid single issue discussions, it's much easier to create arational for concessions.