In 2017 I was disconnected from gaming world, so I can't remember
Initially, all we really new was that it had Mario and Rabbids in them. People assumed it would be a minigame collection cause that's what Rabbids do usually, and the last time Mario was lent out to a third party, that's what happened (Mario and Sonic). Nobody really wanted that, especially because the Rabbids Schtick had worn out its welcome.
One people actually saw the game the response was pretty much "weird but could be good". And when it came out, it got good reviews.
Long story short, people could change their mind.