With few exceptions, they're also supposed to also have mastered their emotions very handily. Partly fue to exceptional biology. Not absolutely constantly be on the verge of breaking into tears or a rage, a la Enterprise.

One thing I think that determines if something is good or bad sci-fi is if the components of the show can be used to look at us humans to improve ourselves. An alien race that doesn't have emotions doesn't give us a vessel to use to discuss issues humans have and how we can improve. A race with very strong emotions who have recognized making decisions with emotions as a basis, rather than logic, is dangerous is useful as a tool to teach lessons.

This is what makes Star Trek good sci-fi and Star Wars bad sci-fi. There are very few lessons to learn from Wars, if any. Almost all of Trek is in service to this (at least in the good shows). It's also why the books of Dune are good, but the 1984 version sucks. The miniseries I think are underrated and more people should give it a try. (It's very campy. Just a warning. If you can watch old Trek you'll be fine though.) I'm yet to make up my mind of the new Dune. It's entertaining, and seems to maintain most of the message from the books, but we're yet to see.

Vulcans lie constantly to themselves and others.

Does Tuvok actually say Vulcans have no emotion? I recall no such thing. I recall them suppressing emotions and not displaying them, but the lore was always that they were a really violent society up until they invented meditation, basically. Right?

Anyway, no matter why or what for we know they technically have no emotions in a practical sense, but Tuvok still displays understanding of the importance of emotions a lot of the time.

Like in this clip

Like "logically" (the "logic" in the show is usually slightly reductive) dancing for someone doesn't change anything. But... we know that it does. So it is logical to do that even if you don't feel the emotions to do it. Although Tuvok does, he just suppresses them, like a good Vulcan.