The title notwithstanding, this is really just a capacity issue, not a GPRS
issue.  In fact GPRS is more efficient for the carrier than CSD or HSCSD.
The basic problem is that demand for data is outstripping supply (spectrum), a
problem that's not going to go away, which is why T-Mobile and Cingular have
turned to WiFi as a cheap way to greatly increase data capacity.