I think you're misunderstanding the purpose of the job fair. In my mind, most programmers aren't great at walking up to 20 random new people; it's draining for people who aren't naturally social (I know it's draining for me). Flipping up the natural order aligns the social people (Recruiters) with the social activities (Cold introduction, striking up a conversation).

For perspective, I'm going to the job fair looking for employees (IMVU Inc, we're hiring, we're awesome).