Title says it all.
If you want to pattern something around a convenient axis, most times you have to first move the move handle to that axis (anchor), then reorient it to that axis (move direction), then select create patterns and...
Selecting the Move radially about axis, then clicking that axis combines the first two steps conveniently, but then you cannot select create pattern; and I just can't fathom a reason for such a restriction?
Besides that its an extra step, if the axis around which you wish to rotate doesn't intersect any other convenient line or surface, then there is no place to anchor the move tool, so you then have to create an interecting line or surface for that and no other reason. Just extra work.