The problem with party-wide buffs is that they're really hard to balance and that they can make stacking a certain AC desirable over any other. I personally still don't get it why Sentinels/Marauders' Inspiration and Trascendence (and their Imp versions) affect the entire party instead of just the user.
Bioware would not possibly be able to implement such a feature without breaking everything else along the way. They messed up plenty of smaller things before.
A) Inspiration only affects your "group" (meaning your side of the ops, max 4 players) and only if they are in-range (30 meters I think)
B) Transcendence only affects in-range members (30m?)
And they affect as many groupmembers as they do because they are party-utility abilities.