It is most certainly a problem for the Chinese. Propping up the U.S. Dollar has been extraordinarily expensive for them...to the point that China, and China's banks, and China's foreign investors, and China's domestic manufacturers are nearing a crisis.
For the U.S., the pain and the economic (perhaps even political) dangers are much less severe than for China. This is *not* a crisis for the U.S., but is merely a small problem.
A small problem that is best addressed sooner, rather than later.
For instance, GM has invested Billions into China. When China re-values their Yuan, those GM products from China will instantly be 40% more expensive. That's going to kill whatever cost advantage that GM thought it was getting back when the Yuan was heavily advantaged by the over-valued U.S. Dollar.
Now granted, General Motors is a mere $16 Billion marketcap U.S. firm, so its loss is really no big deal in the grand scheme of things...but GM illustrates that there is and will be *some* pain for the U.S. due to China's market manipulations.
Moreover, the longer that China goes without re-valuing their Yuan, the more American firms will invest over there because of the distorted economic picture. So the longer this goes on, the more we'll feel the pain here in the U.S. by first losing the business investments to China (instead of being made here) and then second by seeing those investments get HAMMERED by the inevitable Yuan re-valuation.
Instead of the pain that will come from any market manipulation, you seem to be focusing solely on the profits that can be made by the savvy currency traders (some masquerading as corporate businessmen). And it is true that those profits are currently available for the taking.
It's also highly addictive. Easy money and all of that tends to look good, even if it is coming from a temporary market distortion that *will* go away with considerable pain for those most involved.