edit: legit question. what is the allure of playing at clubs like bayern and PSG. two shyt leagues tbh. you know its a forgone conclusion that they will be the league winners. going to either of those clubs doesnt prove anything especially bayern. im a bit salty yes. but they strong arm every team in budensliga into giving up their best players and the team doesnt even really make a great profit to eventually replace said player
PSG and Bayern are a little different. PSG just recently became "the" French club. Prior to that it was Lyon, Marseille and ASSE.
But with Bayern, he's pretty much guaranteed a spot on the wing and the National team as a result (Bayern, like Barca and Real, is a feed for Diemannschaft) . He's already an EPL and FA Cup Champion so nothing left to prove in England. It's also a good move for the German national team. He'll get more game time with Gnarby (who's already cemented his status on the LW for Germany) in addition to Kimmich, Goretzka etc.
Truth be told, as a German player, when Bayern calls you up you gotta answer that call. Same thing will Spanish players and Real Madrid.