Problem with long running anime is they're even less likely to be meaningful. Mainly due to source material - Manga are ran until people stop reading them enough. Same with LNs. So the story just goes on and on until it becomes unpopular enough to have an ending made for it. You can have meaningful stories in them but they tend to not wrap up at all since the characters are what keeps people reading. This is the vast majority and would happen to long running original anime too.
I love having shit like Hisomaso, Sakura quest, Shirobako, Himote house, and the anime originals that come out every season. They're great. Even if they aren't they at least make an attempt at a whole story rather than 'see you next week oh wait we got cancelled'. Let's not forget Ping Pong the animation.
There are exceptions of course, like Kaiba which told a complete story while being an adaptation, and so on, but having shorter anime seasons means that anime are kept tight and to the point, even if there's a lot of similarity.