I know perfectly why. Hunts are the path of least resistance. They require minimal effort in both time and battle experience so of course people are going to gravitate toward that. It is too late now but hopefully Yoshida can do something better in the future.
Remember, you're comparing hunts to dungeons. And by dungeons I mean the 4-man dungeons, not the Primals or Coil.
Now tell me again how dungeons require more effort or battle experience. I would find any attempt to claim the 4-mans in this game require anything other than a tolerance of sheer boredom quite amusing.
The only difference is time. Dungeons require much more time and give often absolutely terrible rewards. No one enjoys hundreds of Brayflox speedruns. This is actually why people hunt. The reason is, quite simply, time. People don't enjoy spending more time than they absolutely have to on boring grinding. Given the option of a faster grind or a slower one, they will always pick the faster one.
The solution was not to nerf the rewards for hunts, and evidently Yoshi agreed because well he didn't. He did alter the behavior of B rank hunts but I still believe that he did that to placate the people who insisted on playing solo instead of partying up for hunting.
The solution was to buff dungeon rewards. Make them drop Myth and Sol which is at least comparable to output from hunt farming, and also for God's sakes get rid of the stupid crafting mats in chests and only have the chests drop gear! If they actually made the rewards from dungeons as good as the rewards from hunting, people who hated hunts would actually do dungeons. Guess what, even the people who hate hunting still don't do dungeons except for their Animus books and their daily Expert Roulette if they are gathering Alexandrite. Because the dungeons suck. This is the real issue, it's just the hunts have dramatically exposed the issue in a way that wasn't visible before because there wasn't an option for grinding besides the dungeons before.