Any pagan ritual/belief/practice that is combined with Christianity doesn't make Christianity better, it pollutes it. It doesn't redeem paganism. It turns the hearts of people from the miracle of salvation and creates a system of works.
I doubt your assertion that Ash Wednesday has pagan roots. I am part of a liturgical church that celebrates the church year along with feasts and festivals. This good order has been built over years. It has nothing to do with works. We are saved by grace, through faith, for works. The good order is a construct in which we operate.
If there is something wrong with the practices of Ash Wednesday, let's hear it. If there is truly a problem, then we need to reform or eliminate the practice. But I have no interest in dismantling tradition because some expert studied history and equates a pagan practice with church tradition. Just search "pagan roots Christianity" and you can drive yourself crazy.