I was surprised that my corporate TA allowed one to be booked. We used to use Concur and that specifically had logic in the search that excluded E fares. Our new booking tool (internal) does not have that logic.
The problem I see with corporations booking this is the lack of residual value of the ticket. If travel plans change at the last minute for the employee no changes/no cancellations can become costly.
Most of the E fares I have seen are in the $200 - $300 range (often closer to $200). Even if they were changeable, there wouldn't be much residual value after the $200 domestic change fee.