I see your point, and the dollar is probably bound to rally for a little while just due to people reversing their dollar shorts.
I do realize that they have this information too. The difference is that they don't use it
They believe the Feds forecasts. They believe that the weak dollar is good for the US. They don't think the current situation is bad for the US economy. I guess it all comes down to how much foreign capital you can attract in the future. If the markets go on a rally than the dollar will probably appreciate. However, I do not think this is the case and that is why I would not hold dollars.
The same would for example stand for the S&P500. If I was American I would have shorted the S&P500 because I see a lot of problems ahead. However, a lot of investors that are a lot smarter than me are long. People are bound to take different positions. Some will be right and some will be wrong. At the end of the day you just have to process the information the best you can and go with your decision.