Per a National Geographic article:
http://news.nationalgeographic.com/news/2014/04/140414-ocean-garbage-patch-plastic-pacific-debris/
"The challenge is huge. For one thing, the garbage is spread over millions of square miles. For another, it's made up mostly of
degraded plastic,broken down by sunlight and waves into tiny bits the size of grains of rice."
"That's what makes it so horrifying," Haymet says. "The micro-plastic is the same size as the stuff living in the water column. How would we ever go out and collect it? So far no one's come up with a plan to separate all the micro-plastic from the living life that's the same size."
The amount of plastic doubles is currently doubling about every 10 years. The plastic is killing tons of marine life. It would be nice if it was as easy to fix as you suggest..