The reason to use semantic markup is precisely because you don’t know what you want to do with the data after the fact. If you, for instance, make all quotes italic, and also emphasize words using italic, how would you later find all the quotes (maybe to verify their authenticity or create source links)? You can’t, since you have hidden the semantic meaning (emphasis or quote) behind a visual style (italic). Non-semantic markup loses information which you originally had when creating the document, and you might need that information later.

Of course, semantic markup is also turning out to be very important for accessibility reasons, since the things people are really needing from a document is its semantic content, and its visual style can be discarded if necessary.

> Our plan is to automatically create parallel content for accessibility requirements

I don’t know. “Separate but equal” seldom works out well.