That seems appropriate to me - makes a function like mouseover into a building block instead of a full featured casting apparatus. As is posted, it lets the macro writer decide how they want the priority for target and me. The error reporting seems a little sloppy, but that seems more a function with the overall error interface on the UI rather than a problem with mouseover that does exactly as it suggests.

IMO, I'd rather that /ac "spell" <me> never occurs during one of my command sequences, so having the primitive mouseover building block makes this possible.