It’s spicy

I have to disagree with you there. Of the many words I may use to describe the taste of vanilla, ‘spicy’ is certainly not among them. ‘Spicy’ is a word I associate with flavors that are sharp and picante, whereas vanilla is, as you said, warm, rich, soft, even a little bit tangy when unsweetened. Pretty much the opposite of ‘spicy’ imo.

I agree with the rest of your description, though. I find your descriptor, “The MSG for the sweet taste,” pretty spot on.