i think you say what you say because you haven't actually delved into anime. I have watched countless movies and series more than 200 anime :P

Anime are basically like movies/series in many ways. you can find anime movies and anime series. You can find anime with a total of 12 episodes and anime with over 100. They also have genres like movies. There are many reasons that you may find boring or hate some anime like the fillers you mentioned among other things but there is an explanation to everything.

For example the majority of the fillers come out 1) because the anime is reaching at the same point as the manga, and they want to give time to the creator to keep on writing 2) because it's extremely popular and they have some merchandise so they "keep it longer" that way. 3) both.

another thing that i want to add is that all those anime that you have mentioned are shonen. Shonen is a category if you want for anime that are targeting to an audience of 12-15 years old, sometimes until 18. Their target groups are teens. You and i were teens when we saw these anime for the first time but we aren't and because of that in a way we have to move on to other anime that are "for us"

not that you can't see these, but chances are that due to being a grownup you will witness a lot of things that won't make sense or seem stupid because we are not kids anymore :P