During Soviet rule the production of cotton in Central Asia received numerous direct and indirect subsidies from Moscow. The wealth transferred from western regions of the USSR to Central Asia exceeded the value of the cotton produced in the region. This transfer allowed Central Asia to develop a much higher standard of living than it could have on its own. In particular the Soviets provided the region with much better education and medical care than existed in neighboring countries.
The Soviet subsidies provided rural Central Asia with a standard of living high enough that its population felt no economic need to migrate elsewhere. The offer of higher wages and other economic incentives by the Soviet government failed to entice rural Central Asians to move elsewhere in the USSR. Many Western scholars attributed this reluctance to migrate to higher paying jobs as stemming from cultural traits inherent to Central Asians. This cultural essentialism of course is known as racism when applied to "politically correct peoples" like Blacks or Jews. Leftist academics, however, viewed it as a perfectly acceptable explanation regarding Uzbeks and Tajiks. In reality their standard of living was already comfortable enough that they did not feel sufficient economic pressure to migrate. In the years since the Soviet collapse there has been large scale labor migration from Central Asia spurred by economic necessity.
Since the fall of the USSR, the economic conditions in Central Asia have deteriorated significantly. In Uzbekistan, heavy indirect taxation replaced the heavy subsidization of the Soviet era. This taxation takes the form of the state (the only legal purchaser of cotton) paying farmers less than the market value for their crop. The state then pockets the difference. Uzbek farmers must meet certain state quotas, the most onerous of which is the requirement that they sow a certain percentage of their land with cotton. In the Soviet Union the state poured money into the cotton sector. Now the Uzbek state extracts wealth from the cotton farms. The result has been a decline in living standards for those involved in cotton cultivation. This has motivated large scale labor migration to Russia and Kazakhstan. An even greater percentage of Tajiks have become labor migrants for similar reasons.
Most of the Central Asian migrant workers in Russia and Kazakhstan are young able bodied men. Many rural villages in Uzbekistan and Tajikistan have been left with only women, children and old men. This has contributed to the continued reliance on child labor to harvest the cotton crop. It has also increased gender inequalities. Men have taken higher paying jobs abroad while women have remained in lower paying jobs cultivating cotton in Central Asia. Few of the professional opportunities available to Central Asian women during Soviet rule remain in rural areas. The Soviet subsidies that supported rural schools and clinics which employed many women have long since disappeared.
The export of raw cotton is not a good basis for economic development. In the US and USSR providing a decent standard of living for cotton farmers has required heavy government subsidies. Other countries such as China and Turkey have moved away from exporting cotton. Instead they have used their domestic cotton production to supply their textile industries which have a much higher return. Both China and Turkey now import foreign cotton to supplement the domestic provision to their textile mills. Uzbekistan in particular is well placed to follow this model. The higher returns from finished textiles can then be invested in other industries. This is a much more promising path than the current one.