devtrackers.gg
its hard because of random who don't know what they are doing
Sounds spot on for the release of any new mode with new mechanics to learn! Additionally, like other have pointed out talents play a part in continually making you stronger on top of general awareness of zombie types, objectives, turret types, and overall strategies.
Casual is the best choice for new players and hard mode will be there for anyone who wants that extra bit of challenge. We'll see how everyone feels in a week or so once many players have figured out tips and tricks .