This feature if brought in, has its good and bad side, good side being you can change envelope of multiple clips to stereo before editing, bad side being, you may already have mono envelope on clips which are clip specific that become stereo in the shape they were before and on the programming part WL will have to ignore already stereo/mono (on convert to mono) envelopes while all clips are selected.
In a montage with 100+ files, it can be helpful to change all mono to stereo envelopes and vice versa.