That's how business works! They won't keep making games if people don't buy them. Thankfully Samus Returns looks amazing so it should sell without much of a problem.
Obviously, but Sakamoto is clearly referring to the disconnect between the vocal online fanbase for metroid and the real world number of units sold in the past. Metroid is great, and one of my favorite franchises, but it has consistently been outsold by other IPs with less vocal fanbases.