However, if we're using – as it happens – <strong> and <em> as direct replacements, we do not gain much on the semantic side of things. "italic" is still an abstract concept to express emphasis, by convention expressed in type by a cursive script font and in handwriting by a single underline. (A double underline would be equivalent to bold and a tripple one to small caps. An alternative method used in traditional typesetting to express the same hierarchy is letter spacing by various degrees. There's nothing in HTML saying that <i> shouldn't be rendered using letter-spacing by a browser. In early browsers, it was a regular feature that the related display styles could be set by the user.)

Edit: I strongly advocate the use of semantic tags like <cite> or even <q> (instead of using typographical quotation marks), lang-attributes, etc. This is only about genuine marks of emphasis (as in speech).

Edit 2: I just learned about the "undeprecation" – so read cum grano salis (<– example of a lateral change of context expressed by the use typographical emphasis).