I'm sure the main reason is people just aren't into it, most of the time people don't really make that clear and instead say it's unoriginal or uncreative(Without giving any reasoning why they believe that), but in reality they just aren't into it.
It's understandable, there's people who just don't like or get the idea of using something that looks human when you yourself are human. And for inanimate objects it's probably more a case of you are familiar with it not being living but in Pokemon it's basically living. You can pet a magnet like you would a Cat in Pokemon, and it is a little odd when you look at it that way.
Personally, I love all types of Pokemon, Magnemite and its line are one of my most favorite Pokemon and I love a handful of others like it. And on the humanoid look, Gardevoir is one of my favorites as well. There's a bunch of people who aren't into it, but at the same time there are a bunch who are(I'm sure most prefer the more Animal-like Pokemon though but still have plenty of favorite for inanimate and humanoid).
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