A point of contention in this one is why Spock would struggle with his human emotions, when Vulcan emotions are supposed to be "stronger." I don't think there's been any suggestion in the past that emotional control is a Vulcan genetic trait.

This is given some cover within the episode, when Spock vaguely says that the human emotions are "different," but he doesn't elaborate.

I wonder if, in keeping with Spock's character in the franchise as a whole and in this series in particular, Spock's predicament allowed him to subconsciously give himself "permission" to embrace and explore his emotional side, with the genetic alteration as an excuse.