We know that Spock is biologically half-Vulcan but to me he looks just like full-Vulcans. B'Elanna Torres is half-Klingon and half-human, but in her case you can tell; the Klingon traits like head ridges are about 50% of what they would be were she a full-Klingon. So, shouldn't Spock have only kind of pointy ears, sort of slanted eye-brows, slightly green blood, etc. instead of simply looking just like a full-Vulcan?
In the original Star Trek, Spock's appearance was simply that of a human with oddly trimmed eyebrows, green-tinted skin, and pointed ears.
In contrast, his father Sarek has much heavier eyebrows, much more oddly pointed ears, and a heavier coat of green makeup which additionally gave his skin an uneven quality.
When I first saw the episode "Journey to Babel," in which Sarek appears, as a kid, I was immediately struck by how much more alien a full-blooded Vulcan looked than Spock.