I hate CM Punk as a heel
the guy had potential to be a poor man's Steve Austin
No he didn't.
He has to be heel in pg era because of the bullshyt they do to neuter characters. Punk's not a natural "smile and wave" kind of guy, which is the face template they have. So just him being more his natural self has him back in heel territory.
No one could be another Austin, even a poor man's, in the pg era because everything that made Austin what he was isn't allowed anymore. That's why face Punk always had this kind of "that's it?" feeling leaving you wanting more when he got into confrontations. Like when he was going against Funkman, they'd be face to face and everyone just wanted to see him call Johnny a stupid son of a bytch and beat his ass like Austin used to do to Vince. But in the pg era the most you can do is crack some corny jokes and smirk for the audience.