This is false. X is not less secure than Wayland. It does have a different security model, which can become insecure if you misuse it. I don't think people really care about situations where multiple user accounts access the same display.
In my opinion, the benefits of xdotool far outweigh any benefits gained by Wayland's security model. It's impossible to make xdotool in Wayland, because of its security model.