First off, you're getting upset against a casting decision on a 50 year old show, a show that is generally lauded for diverse casting. Secondly, Leonard Nimoy, depending on your point of view, wasn't "white". He was Jewish, a historically oppressed minority (witness Patterns of Force).
Should I not feel empathetic while watching Roots because I'm not black? Maybe I should only feel guilt instead? You have a sadly literal notion of identification and empathizing.
You can't have a story without conflict. When the story takes sides for the viewer and doesn't allow any gray in the middle, that's when it gets too ham-fisted.
First off, why do you think I'm upset? I didn't write my statement in ALL CAPS. If anything it seems like you had an emotional response to my speculations here. I was commenting on the STC episode and beyond that about the weaknesses of having Spock be a stand-in for non-white people. I never said Nimoy wasn't white, I don't get where that's coming from. It's established that his mother in the show was a white woman, so Spock was at least have white, and add that to his fair-skinned Vulcan father. Though to be fair, there was supposedly enough ambiguity with Nimoy's appearance that Kirk could call him a "Chinese rice picker" and expect that to fly in 1930s America. Fair enough Nimoy was Jewish, a member of an oppressed minority (in this case of fair-skinned people). Shatner is also Jewish, do you think he would work as a stand-in as well?
As for Roots, I don't know how people approach that or if they feel empathy regarding the treatment of Africans at all. That's not my job to determine that, and I never said it was, so don't try to put that on me. I don't know if people identified with the Africans or the slavers, or if they tried to find some middle ground there to sympathize with both. Race and the history of racial conflict, in the US, is a very knotty, complicated issue, and it produces a multiplicity of feelings. Though if you did feel guilt is that bad? If we can feel pride in the past, if we can take pride in what happened in the past and feel a sense of collective achievement, then can't we also feel guilt and shame for the darker aspects of history? If we have a collective responsibility to push forward the ideals of the Declaration of Independence and the Constitution then I don't think its a stretch to believe there is also a collective responsibility for the great crimes committed, which include the the treatment of Native Americans and Africans.
It's debatable about what's ham-fisted or not. I think that depends sometimes on if the show or movie has a view that you (not you personally, just in general) don't like, then it's ham-fisted. Using Star Trek as an example, there are episodes where it does take a clear moral line in the sand. So much so that shows like "In the Pale Moonlight" stand out so much because it does dwell in shades of gray. And throughout television period, I would argue that a lot of dramas take a side. And the conflict is more about the hero accomplishing his/her goals instead of it being a shades of gray situation.