The empathy factor might be bull from an objective standpoint, but consider that the suits in charge thought that Spock was too alien for viewers to connect with.
The suits in charge of Star Trek also thought America wasn't ready to see a white man and a black woman kiss onscreen, which is one of many reasons why it's my considered opinion that 90 percent of the suits in charge of anything deserve to be sodomized with telephone poles.
And what's especially funny about your example is that Spock became THE MOST POPULAR CHARACTER ON THE SHOW, so their "logic" doesn't even work from A PURELY MERCENARY CAPITALIST STANDPOINT.