Like others have stated:
- The adapter in the standard SR45 set (actually for any Muteki non-locking set) is just an English-to Metric converter. (3/4"+13/16" to 17mm hex) Nothing special about it. It's not a lock or key.
- The locks give you peace of mind. They are actually keyed based on a set of 16 or so different unique patterns (I'm not sure the exact total). Each set of 4 locks share 1 key. However, any competent thief who actually targets the wheels will be able to get away with it. It will only deter the opportunistic thief.
I've run the SR35 and SR45R with optional locks. I would hate myself if my wheels got stolen one day. In my mind, if I at least put locks on them, I can live with the fact that I actually tried to do something.