Now that I've had time to think about it, I can't really blame them.
In previous expansions new 5-mans tended to serve as a mechanism to gear up your character outside of regular raiding, as well as set the stage for the associated raid. This was all well and good, but LFR allows players to raid current content without being part of a regular raiding group and scenarios can do just as good, if not a better job at setting the stage for the raid instance.