Okok...it's regulated. A regulation that has been in place long before the current state capture was planned. At least in the current climate, change to the Constitution is alot harder than via government directly which is a good thing right now, not a bad thing. Its really not unreasonable to assume that such power would be missused. The ANC has time and time again shown that economic sense and the well being for all are not always their top priority. Whether its the various finance minister changes for reasons clearly against economy and the jobs that go with it, or the current thoughtlessness of the new mining charter amendment, which simply further enriches the same guys over and over again.
In this spirit, if truly a serious and beneficial change were to be thought of, it would easily pass the votes needed for a change in Constitution right? In other words the much needed change (I agree with you on that) requires political will, not changes to who can amend SARBs mandate.