Yeah that's right but more NGOs who deal with agriculture there try to propose new plants to grow, particularly the ones that can provide food.
Now it's also a good idea to buy the opium for medical purposes but by encouraging people to grow more, NATO takes the risk to control even less fields than it currently does - hence giving it to the insurgents.
Another problem is that the money with which NATO buys the opium goes to the farmer who is sometimes pro-insurgents or against but does not have any other choice but to give his money as blackmail or ransoms.
It's nice to try to turn the current situation to your favor but they really need to stop sending mixed messages and work against each other. Sponsoring opium is not the way to the future for Afghanistan... it draws criminals as flies on shit.