Hello,
Yeah– unfortunately that is the case.
However, in our next major Pro release, v 1.4.0, there will be admin options for simplifying the Variations / ability to disable some of the options. So you will be able to apply your restrictions once version 1.4.0 is released (should be by the end of March).
There are not currently any filters in that area of the code either- otherwise I would help you remove them with filters.