Well, we got tired of writing the e-Books. While we can spend short periods of time at our computers writing message board postings and blog entries, trying to write an entire book is just too hard.......
On a more serious note, I'll offer up the same answer I provided on the S&S board when a similar question popped up. I provide this with the caveats that a) circumstances may have changed since I was given this info and b) I may have misunderstood what was told to me. Anyway, what I wrote was:
"As it once was explained to me (not sure if this is still how it works), the e-Book file is made available to the different vendors who sell e-Books via their respective proprietary formats in time for the e-Book version to be available on or about the dates the printed versions begin showing up in stores. Once S&S does that, it's out of their hands and up to the individual e-Book vendors, who convert the file sent to them into whatever format they're using, adding in whatever bells and whistles go with a particular format, etc.
As for why the individual vendors are dragging their feet...that's a question for them. Maybe they're backlogged in prepping e-Books for release."
Something else I thought of (and I have nothing to base this on) is that perhaps the different e-Book vendors prioritize what they prep for release based on past sales history of related books. If Trek books aren't big sellers, perhaps they get shuffled out of the way of books which are viewed as being better money makers.
Maybe somebody else with better knowledge of the process can chime in and clarify or correct my comments as appropriate.