Reverse blocking IGBTs no longer available, why?
I imagine it has to with costs and volume production. To make power transistors competitive they need to be mass produced and reverse blocking capability is just not the main use of an IGBT. IGBTs main use is as a switch in a three phase inverter, and there you don't need a RB-IGBT. Nowadays IGBT are being replaced by SiC-MOSFETs in the 600 V-1200 V market, so I expect that IGBT manufacturers will not innovate much more either.

PS:PT and NPT refer to how the electric field inside the device behaves, that doesn't imply capability to block voltage in third quadrant operation