I’m always happy to attend if you need me, or if it will simply make you more comfortable (assuming I’m available on that day and time).
Normally, the wedding coordinator conducts the rehearsal. Since you won’t be going through the actual ceremony, it really isn’t essential to have your officiant there – unless (1) there’s no coordinator to run it for you, and you’d like the officiant to direct it, or (2) your wedding contains unusual ceremony customs which really do need to be practiced beforehand.
Please note that there is an additional charge for attending a rehearsal, as it means going out to the location more than once, and does require extra time.