Ask anyone in digital publishing today and they will tell you that Epub is the be-all and end-all of document formats. This ones-size-fits-all format can do anything (just ask Bill McCoy).
Or, you could look past the propaganda and realize that there are better formats. PDF, for example, is better than Epub in many ways.
Here are four (out of dozens, so if you know of other reasons please feel free to leave a comment).
#1 PDFs can be read on any platform
Pull a computer out of the box for the first time, and try to read an Epub on it, I dare you. When that fails, search for the user manuals on the hard disk. Guess what format they're in?
If you said anything other than PDF, you'd be wrong.
Name any device, beit a cellphone, smart fridge, pez dispenser, , and odds are good it can read a PDF. (And if it can't, it won't be able to read an Epub either.)
#2 PDFs can be made with just about anything
Not only can you make PDF as a print/export option for office suites, cloud office services, note-taking apps, it's now a standard printer option on Windows 7. Tools to make PDFS are literally everywhere, embedded in every type of app.
Got a Touchpad, a Twinkie, and a tissue? You can make a PDF.
Got an old Psion handheld and a couple of Q-Tips? You can make a PDF.
#3 Epub 3
#4 Compatability & Accessibility
Have you ever tried to take an Epub from say, Apple's proprietary Epub format and convert it to say, Kobo's proprietary Epub format? Ever try to extract the content from a fixed-layout Epub?
It goes something like this: