Someone who gets a bad unit is going to show up here to complain.
Someone who gets a good unit is not going to take the time to tell others they got a good unit.
If you got a bad unit and read through this forum, you might get a skewed impression of the fail rate. I don't see a reason to doubt the official statement about the percent. If a majority of MiniBrutes had broken key beds, they would be rare - piled up high at a return facility and in repair shops, and few in the wild. Yet we know people have flawless ones. Are there about 25-50 unique threads about broken keys here? That's a small percent of sold units.
Go visit the forums of other synth manufacturers. They are filled with complaints and horror stories, from firmware to hardware to basic functionality. Go visit the forums of any complicated product, from washing machines to smartphones. There's always someone saying a product is "junk."
Not discounting your experience. I had the same thing happen, but I decided to superglue the bumpers in place.
I'd like a replacement key bed, and maybe that will be the eventual solution - anyone registered can sign up for a free replacement key bed and self-install instructions. That would suit me fine.
Try another return, and hopefully you'll luck out. If not, Arturia has promised a solution.