From what I was told, they created the 5k and 10k standards as entries to the olympic marathon trials in attempt to motivate the shorter event talent to move up into a distance they could be competitive on the world level.
The half marathon is a fringe race in a sense that the majority of the top talent the runs them come from the marathon distance dropping down, not coming up from the 5k/10k ranks.
If what I was told/read was correct, they really don't think that those 5k/10k guys will make the marathon team. It will just introduce them to a new event so down the road they can do something big.
Like others have said, opening up the half marathon window to qualify might allow for a bunch more new qualifiers. Could be a good thing, could be a bad thing.
If they open up a new window for people to qualify threw, good for them. No special treatment for someone like Cox though.