[0]recommended: Stein's Gate, Psycho Pass, FLCL, Serial Experiments Lain, Tatami Galaxy, Pop Team Epic, Cowboy Bebop, Akame Ga Kill, Panty and Stocking with Garterbelt
1. This quality is unique or more common in Japanese anime
2. This is a feature of all media of which Japanese anime is one
If the answer is #2 then there was no reason to say it. It would be like saying "water is wet in Japan". Of course water is wet everywhere so no point in even bringing it up.
If it's #1 then we need proof that Japanese anime has more clones than other media from other countries. I think that proof will be hard to find. Crunchyroll is not Japan.
There is a lot of anime I would rate much higher than pretty much any other narratives presented in other media formats including my native Hollywood.
Heck let's take western indie games where a large percentage of all indie games are yet another smash brothers clone or a metroidvania clone. There's probably at most 3 more genres that make up the majority of titles
In other words that there is tons of derivative stuff is not even remotely unique to Japan.
There's tons of anime that doesn't make it out of Japan (or used to be) as well of tons of manga that's seriously creative. Walk through a Village Vanguard store for example.