I was reading recently about technical failures due to miscommunication. Did you know, for instance, that the Mars orbiter crashed because some design team members were using the metric system while others were using English units? This had led universities such as USC and MIT to highlight the need for negotiation and people skills (or "soft skills") to their engineering students.
Very often, design teams will need to reach a consensus among themselves. Despite having the same goal (be it to design the best car or the Mars orbiter), engineers will inevitably disagree during the process of design. They may also need to interact with or present their ideas to non-technical teams.
Working on a team is a topic in itself. (See my chapter in Professional Techniques for Video Game Writing for more thoughts on that topic!) The very multidisciplinary nature of game design ensures that "soft skills" are necessary.
What other skills do you think are preferred or necessary for game designers on the job?
Give me your thoughts. Or if you have something longer to say (500-1000 words), send them to me as an article and I will post it up!