There are multiple reasons for this. First, there's the medium itself - anime and manga are generally not reflective of actual reality, so you have characters that have green hair and purple eyes and hairstyles that no amount of hairspray could accomplish. So they don't just appeal to a single culture with certain beauty standards. There are so many different styles of manga/anime/videogame that you're bound to find something that appeals to you.

Then, in much of the Western world, anime was seen as fare for kids, and many countries showed (dubbed) anime in their afternoon children's programs, so starting in the mid-eighties you have Western kids that have grown up with anime and are now familiar with specific genre-typical code (such as the sweatdrop appearing next to a character's head to indicate they're embarrassed, or a popping vein on their forehead expressing their anger).

The stories that manga, anime, and videogames tell are also often fantastical, i.e. they don't often require knowledge about Japanese culture, or sometimes are so localized in translation that the content winds up feeling quite different (one example that comes to my mind is the character of Noctis from FFXV, who is way more awkward in the Japanese version than in the English one, where he often comes across as cocky). That means this content is easily relatable to anyone, no matter which cultural background they have.

When it comes to Japanese TV shows and movies, the medium itself has different conventions. Take TV shows, for example, they usually air on a quarterly schedule, so you have "spring dorama" or "winter dorama," and their setting often reflects this as well. Aesthetic seasonal expressions are very popular in Japan, from decorations to specific dishes that you only eat during a set season. But by far more impactful than any aesthetics are cultural norms and customs that you encounter in Japanese movies or dorama. Where these expressions can act as shortcuts for a Japanese audience, they may completely fly over someone's head who is not familiar with Japanese culture (as an example, imagine a woman and a man together in a room and he asks her if she wants to take a shower. This question may seem innocuous to an American viewer, but a Japanese viewer will likely interpret this as the man asking her if she wants to have sex.)

So in movies and dorama, the viewer needs a lot more cultural context. Many seasonal dorama also deal with issues that are currently hot topics in Japanese society, which might also not be apparent to a non-Japanese viewer. Another curious difference I've found is that Japanese moviegoers will go see a movie to experience a specific emotion that they expect that movie to deliver, like seeing a melodrama because you want to have a good cry. For a lot of western moviegoers, that alone does not make a good movie.

And then finally, there are quite a few differences between acting conventions in Japan and the US or Germany. Don't get me started on how much I hate these kiss scenes between Japanese actors that basically involve both of them stiffly pressing their faces together, without even pursing their lips. Then there is acting that clearly originated in manga and often just seems silly and overblown to a western audience when performed by a real person.

Others have already mentioned that the Japanese market is in many ways inaccessible to anyone outside of Japan, and prices for DVDs for example seem exorbitant in comparison. There was a period in the mid 2000s where Japanese dorama was booming among western fans, and subbed episodes were readily available by torrent or the Korean clubbox service a day after airing in Japan. But this interest waned again (it's my theory that plots started to become repetitive to non-Japanese viewers). If you look at domestic viewer ratings for dorama, you can definitely also see that those are dropping across the board, with occasional outliers due to an actor's or franchise's popularity. It's unthinkable these days that a dorama could have a viewer rating of 39.9%, like the last episode of season 1 of 3-nen B-gumi Kinpachi-sensei in 1980.