Remember when (the original TOS) Spock was faced with Kirk's death in "Amok Time"?--a time when his Vulcan emotions were very much at the surface due to his pon farr--Spock did not scream in anguish or yell at the killer (himself). He kept himself in check. And even later, when he found out Kirk was not dead, he only reacted with a "soft" shout--and then quickly got himself back into control within seconds. Yet this nuSpock lost so much control that he went on an almost murderous rampage to attack Khan
That's exactly how I feel. Having Spock lose his cool is a gratuitous and unsubtle way to handle Vulcans. It's like JJ thinks that's what the audience really wants. In TOS, they rationed out the moments where Spock lost it very sparingly. Elsewhere, Nimoy underplayed little hints of emotion here and there. Looking for those traces of emotion in every little pregnant pause and eyebrow raise is the entire appeal of Vulcans in Star Trek, not just having a plot that pushes them over the edge.
For instance, when Spock is emotional after the V'Ger mind-meld, it made sense because the entire picture revolves around the existential question of pure logic vs. emotion. That's why one of the first scenes is Spock about to accept the Kolinahr, and then refusing. But this film doesn't delve into it, at least not that deeply, besides a few decent lines with Uhura inside their Millenium Falcon ripoff, where Spock says that a big part of the appeal of holding his emotions back is to prevent the pain of grieving over the loss of Vulcan.
But that's a very egocentric way of looking at Vulcan philosophy. Spock is supposed to buy into the logic thing on its own merits, not simply as a way to handle PTSD. So this is kind of a bastardization of the character and a reluctance on JJ's part to fully embrace the philosophy as a valid way of life (at least for some).
Kirk accepted Spock despite Spock's seeming indifference. Ultimately Spock having a different way of looking at the world plays into the diversity theme, and to open people's minds about other ways of thinking. But JJ kind of wants characters (like Uhura, by nagging) or situations (like Kirk's death) to show Spock the error of his ways. The whole idea of Spock is that he can be seemingly unemotional AND a good person at the same time, even a good friend. There's nothing wrong or broken about him. You just have to understand him on his own wavelength--without needing to actually see him cry or laugh. So I think JJ sees Spock's logic as a character flaw rather than a virtue or a point of diversity.