according to the "who pays for GF" thread, there are people who have sufficient disposable income that they are apparently happy to burn it on GF.
Of course these people exist, but they are near unicorns. The thread exposes that they are willing to pay HOD to low TOD for upgrades to GF
Adding in 2-3 J seats in place of 1 GF coffin is a clear revenue win for the airline, and just dump the PAX who will fly someone else GF