Aguero just said what anyone thinks. Bundesliga is shite and scoring a bucket load there should be followed up with consistent performances in a better league, like LL.
Has he played there?
No - so what does he know?
The question is often about the system and in which team you play. Chelsea's system e.g. makes it far more difficult to score goals for a striker than Liverpool or Manchester City despite being in the same league - I would not even take a comparison between mid and top table teams as a striker in a mid table team that plays with less possession might have it a lot easier to score goals than the striker at a top team with more ball possession.
The thing is - teams sit as much back against Bayern as they do against Barcelona - or fight all over the pitch (and the referees are lenient as it is top team against the smaller team). The high scoring matches usually are the ones were you are lucky to score an early goal and the opponent opens up - but small teams often do not even do that. Bayern right now e.g. is the team that is 17th team in the Bundesliga ranking for being fouled. Nobody can tell me - when a foul often is the only way to stop players like Coman, Sane etc. that the refeering is pro Bayern despite the situations that are cooked by the media for days when Bayern profits of a referee decision.
The Bundesliga itself among all the other teams is living of a lot teams that are very direct and have a very good pressing and counterpressing. Somehow there is lately not many teams that you clearly can put a bet on as about everybody can beat everybody so less teams have a really defensive system approach. That creates more vertical play and better goalscoring chances. And like this - yes, there is more goals and it often is easier to score goals for the strikers. But actually that does not make it easier for a striker in a team like Bayern for which the match for the opposing team is the match of the year where everybody is motivated over the odds and teams run their asses of. And a team like Bayern for sure is not motivated to go 100% in every match...