GIRM 146 would lead me to believe that the priest shouldn’t be making this response, since the response belongs to the congregation:
- Returning to the middle of the altar, and standing facing the people, the Priest extends and then joins his hands, and calls upon the people to pray, saying, Orate, fratres (Pray, brethren). The people rise and make the response May the Lord accept the sacrifice, etc. Then the Priest, with hands extended, says the Prayer over the Offerings. At the end the people acclaim, Amen.
A lot of the rest of what the priest prays during the Liturgy of the Eucharist – his quiet prayers and the Eucharistic Prayer itself – have to do with asking God to accept the sacrifice, so on the one hand, it’s a bit redundant for the priest to pray the “May the Lord accept” prayer… but on the other hand, the Roman Rite has a fair bit of redundancy in it: have you ever noticed how many times we ask God for peace? Try counting that sometime, if it doesn’t distract you too much.
But this is a small matter, the priest saying this response.