Pandaren are the most fleshed out race/culture in the game next to Trolls, so they were implemented amazingly well. The only people who complain about them are try hard teens who think anything other than medieval knights and magic is gay and for children.
It's like saying there was nothing but knight's in the 10th century while ignoring the other half of the world.
Also BfA is the PERFECT time to add some Pandaren story, they need to give us some facts on why the Pandaren on either faction are now willing to go to war with each other. Same goes for DK's and DH's.