The game was massive, the panda option came from an optional campaign in TFT and the panda itself was optimal in the optional campaign. The other times you saw them was in passing as NPC. Nothing special there if you ask me.
What hilarious is people making them out to be bigger than they were.
I can agree with that.
Writers can do anything but if the next expansion is the "RETAKING OF THE CANDLES" and we play rat people. It's not likely to be perceived really well. The writers for blizzard did a pretty good job bringing them from relative obscurity and into the light but for such a minor roll in warcraft and no real role in WOW the MMO. Shocking they went with them.