Could playing as different Pathfinders have worked?

I'm not entirely sure what you mean here.

DA supported other species as the PC from the beginning.  Not terribly difficult for the DA team, since all of their species have similar facial features and expressions.

AFAIK, the ME team has never suggested they would consider supporting a PC of any species other than human.  I can't see them ever doing that, though they could potentially be willing to consider producing a DLC where you play a character of another species (though I wouldn't expect that character to be highly customizable).  Or perhaps a segment where you play another character, similar to playing Joker during the collector abduction in ME2.  Other than that, I can't see it happening.

The other thing they (ME development team) would need to consider is the face-scan technology they implemented for the CC in MEA, and the non-existence of other species to scan IRL.  Plus, all the backlash from people who were dissatisfied with the CC they released.  After all of that, I'm pretty hard pressed to imagine they'd want to try to build CCs to support multiple spec