I think Herb has mentioned over and over again that single faction books don't sell particularly well. I figure you have two choices. Keep creating combo-faction books like the FMs, or smaller single faction products like TRO 3145, but with some sort of combo-set for those who want a more complete book. By tossing in a few goodies a print-only product doesn't seem like a rip off IMO.
Personally, I think this was a better deal than say TRO 3055 or TRO 3067.