[exaltedwombat]

No, really, this is interesting and very pertinent. I have NEVER been asked for "epub only". I've never been offered a budget sufficient to prepare two separate optimized versions (and why stop at two? The new crop of tablets, with their various reader applications, have their own set of quirks). The practical name of the game is making code that converts elegantly to a range of devices. Unfortunately, this, in practice, means abjuring layout features that don't.

So "How will this convert to Kindle" is an essential question when preparing a book. Otherwise we're like the (fortunately dwindling) band of Mac-using web designers who when told "This site is broken in IE" smugly reply "So what?" :-)

Of course, once InDesign users catch on that they also could write simple code that converts cleanly through its "Export to epub" function, a lot of employment will disappear.