game of thrones - Why does Jaqen H’ghar still look like this guy?

To give Arya (and the audience) a familiar face that she can relate to. Mostly the audience, as this never happened in the books. Being a Faceless Man, the man who calls himself Jaqen can take up any face at all, but having a different face would confuse the TV viewers. Unlike books, TV is very visual so the show runners have to make different decisions when adapting the story. Thomas Wlaschiha's portrayal of Jaqen H'ghar was very popular with the fans. Having Arya's trainer be Jaqen H'ghar with his familiar face is a huge draw for the audience, and it ties up the story of Arya nicely.