Certainly the level of Theoretical Knowledge required for the CbM IR or EIR (it's the same for both) is considered to be a significant deterrent.
FCL.800 reduced it "By as much as we thought we could get away with" (as it was described to me by one of that working group). Which was by about 40%.
However, the EASA group members with whom I'm working all consider that a review and reduction in the Theoretical Knowledge, perhaps to a level parallel with that required for the FAA Private IR, is very necessary.
Frankly it doesn't surprise me that the EIR hasn't had many takers, but we need to see whether that will change if the level of mandatory theoretical knowledge is reduced.