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I think any Shonen fan should watch DB/Z since they were basically the framework for Shonen media henceforth (Dragon Ball presenting the Adventure side while Z represented the fighting side), without feeling too old or dated in the process. The unique thing about them is that while they can be said to be responsible for many of the cliches that exist in Shonen today, they aren't directly responsible, and you will find that many of the aforementioned cliches were born from the generation of anime/manga that DB/Z influenced. And, on the pro-side, it ended up influencing and creating many of the nuances and conventions in not just Shonen, but anime as a whole (and really media as a whole). It's interesting to think about where anime would be without it (and how anime would be seen in the West). So, even if you don't like it, it still manages to be a revolutionary piece of work.
Having said that, if it weren't for Toei, there wouldn't be nearly as much filler in the industry, so take that as you will :/