Why is the value of the yuan relative to the dollar so important

Why is the value of the yuan relative to the dollar so important? If you were the CEO of Wal-Mart and were preparing for a meeting with the most vocal members of the US Congress on China’s currency “manipulation,” what would you say to them? Assuming that the yuan will appreciate further against the dollar, what should Wal-Mart do? If you were an exporter from Argentina, Indonesia, Malaysia, or South Korea and selling to China, would you accept payment in yuan (instead of dollars)?