I get the allure of it. If I could go around Getsuga Tenshouing or Cero-ing enemies, I'd probably like it...just because that particular action is what I'm doing. I'm interested in Bleach, so I'd play something with Bleach stuff in it. Running with the anime theme I started, J-Stars Victory only got a 32/40 in Japan (a region that favors games like that the most). If it released in the west, surely it'd get much lower scores and be an "average" game. But I'd still play it and rave about how awesome it was to throw a Rasenshuriken at a Kamehameha.
Dynasty Warriors is plain and generic, but people who like Zelda attacks and lore would be more interested in it.
Objectively, yea, Hyrule Warriors is just Dynasty Warriors with a Zelda skin, so overall, it's a mediocre game. But I "get" why it's being praised