The new extended mnemonics for existing instructions are just to make it easier for programmers, as usual, once they can rely on having the appropriate level of HLASM.
I have been asked more than once why there isn't an LFI instruction and had to point users to IILF which does exactly what LFI would be expected to do, so I suggested the alternative mnemonic to the architects myself. They agreed with the suggestion, and suggested similarly LLGFI for LLILF, and also called to my attention the extended shifts which had previously been requested but not implemented. Jonathan Scott, HLASM IBM Hursley, UK