It seems with the current state of Necrons flayed ones were sent back to the tomb world to wait for a new codex. Sure they have terrifying visage but who isn’t fearless these days in 40K- and if you aren’t fearless you are riding in a tank. Not only can’t you shoot with flayed ones, they suck in the assault- an extra attack- no jacked out I, no rending, no power weapons, no invul. save! On the other hand they are “Necrons” so at least they add to your phase out number.
That said, I could still see a use for them on the table- one unit ten strong only as a distraction to keep your opponent busy, but not for long as they won’t be much of a distraction. Outflank them, infiltrate them, or deep strike them for objective grabbing and then go to ground. With a 3+ cover save and WBB they can stand up to some shooting for a bit.