It is my suspicion that groups like the World Uighur Congress (which receives nearly $1 million funding from the US government) is afraid that economic conditions in Xinjiang might improve (as indeed, household income has been steadily rising over the past 5 years); because improved standards of living will hamper their attempts to promote separatism .
Here is where you have to decide your loyalty. Do you care more about creating an non-viable East Turkestan, or do you care more about improving the conditions of the Uighur people?