GMO seeds and weedkillers - Why did Monsanto engineers expect they could beat the power of evolutionary forces?

From http://crooksandliars.com/susie-madrak/weeds-are-now-resisting-monsanto-weed

Monsanto sells genetically modified seed that’s supposed to survive spraying with their weedkiller. Unfortunately, the weeds learned to resist it – and now their GMO seed is struggling against the pesticide-resistant weeds that evolved as a result of their own product.

Just as the heavy use of antibiotics contributed to the rise of drug-resistant supergerms, American farmers’ near-ubiquitous use of the weedkiller Roundup has led to the rapid growth of tenacious new superweeds.

To fight them, Mr. Anderson and farmers throughout the East, Midwest and South are being forced to spray fields with more toxic herbicides, pull weeds by hand and return to more labor-intensive methods like regular plowing.

What is your opinion about the future of genetically modified organisms?