For me, starting with DOA2, Ein users online scared the crap out of me. Every hit was a blowback, quick as hell, and every counter and grab was brutal. I wanted to use him from that point on so I could be the one panicking my opponent and putting them on edge. Hayate has very little of that power and intimidation. Just my two cents.
Free Step Dodge
AegisOrnus
XZero264
Ein > Hayate. A much bigger force to be reckoned with because of mentioned knockback and much more reliable combos and damage (coming from a guy who has second mained him since I got 2H 11 years ago). Plus he hasn't shown up in 5 until NOW!!!