BCF's, Beating the Dead Horse

Why dont we have some BCF, like the 737-800 BCF ? we have the 757-200SF with is a converted 757-200 passenger variant? I know this has been started, but i dont see why these cant be offered as new or just do like the -700cs do where you clear the seats?
thanks in advance

Even if its called a 757-200PF/SF in game, its gross payload is roughly resembling that of a 200PF (39,000kg that is), not an SF.
The PF was a factory fresh built freighter while the SFs are converted pax airframes.
The thing with converted pax airframes is: there’s no fix data for payload etc. as that all largely depends on the donor pax airframe.