Just for the record, the example in that article is not about serif vs sans-serif. That was just the simplest example possible. The "Ew" means, "it didn't do what the standard spec says it was supposed to," NOT "I don't like serif fonts".
Whether or not ePub lets a book designer choose a font is not up to Apple. ePub is a published standard that Apple pretends to support. The point of the article is that Apple lets book designers choose fonts for many elements in a book, but not all. This is completely non-standard and will lead to hacks.
Whether you would like Apple to choose 6 fonts for you to choose from, or book designers to offer different choices is completely beside the point. Or at the very least, a very different point.
Whether or not ePub lets a book designer choose a font is not up to Apple. ePub is a published standard that Apple pretends to support. The point of the article is that Apple lets book designers choose fonts for many elements in a book, but not all. This is completely non-standard and will lead to hacks.
Whether you would like Apple to choose 6 fonts for you to choose from, or book designers to offer different choices is completely beside the point. Or at the very least, a very different point.