In this I have to agree with Berto, one of the main points on DMC canon is Dante's humanity, the greatest gift his mother had given him. If she was other kind of person or had someting special it would be told.
We know too what Dante cherishes most is his human soul. If Eva was a witch, that would mean she had sold his soul to a devil, for whatever reason, she would be exactly like people Dante despise: those who sell their soul for power or other egostical reason.How would Dante deal with it?
About creators trying to acting or interfere with a canon or creation they hold no more power: this lead me to think this reboot, this erasing from the older canon, was partially made to avoid Kamiya's constant intromission on something that it is not his anymore.He had his part, he was reluctant to continue and now seems so obsessively attached to something he should let go.