Honestly my guess is the next main series Metroid is being made for the NX and they decided to put out this spin off as a "low impact experiment." It's on 3DS so the dev costs are lower than they would be on a home console, so they can kinda afford for it to bomb should reception to the final version end up negative.

Right now this is mostly just a bad knee jerk reaction with enough salt to supply a fancy restaurant a few times over. I think if we just give it time people will realize it's just a silly spin off game and might warm up to it. I sure, is this what I wanted? Hell no. But am I going to be all like those YouTube commentators (I went into hell today… was not a good idea) saying "OMG FUCK U NINTENDO U SUCK I HATE U 4EVER GAHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH!!!!!!!!!!!!!!!!!!!!"? Also no. I'll give it an honest chance and if it's actually fun I'll say "well shit, it's actually not bad," but if it's not I can just go "eh it's just a spin-off, I'll wait for the next main series entry."