It would’ve been a lot more forgivable for a film to be so derivative if it hadn’t been made by someone as visionary as James Cameron and with as much money as it had behind it. Truthfully, the main reason for Avatar’s mediocrity is, even though it made billions of dollars in the box office revenue, the real reason it exists at all is because of the tech that was developed in the process. Avatar is pretty much a gigantic research and development project for the real time rendering engine and 3D projection system. Plot and characters aren’t as important when what you’re really trying to do is make new technology for the patents. That’s why they’re doing sequels, even though there’s no real fan base. Cameron is really gambling that whatever new tech he develops will be worth making four sequels nobody wants.