Pretty much took the words right out of my mouth.
There are already tons of ways for players to interact with the open world. It is lush full of content, and they just choose not to do it. Adding fresh content won't sustain interest in it if it does not serve to provide towards player's long term goals, or if more efficient means exist elsewhere.
If more players instead interacted with each other in the open world, it would draw more players into it. The game even adds audio of a noisy crowd when enough players are herded together that I find very encouraging. It sucks when players are shouting at each other when an elite mark is pulled early, but at least they are interacting with one another. It would be awesome if a positive spin could be put on something of that caliber. Right now though, every time I bow and say thank you to a random who helped me bring a mob down, their usual response is to whistle for their chocobo, and fly away.
In short, if we want the open world to be more active, we need to actively spend more time there. Simple as that.
