Why should there be "middle ground". LFR is the lowest level of raid difficulty and is being released AFTER the medium mode?
There is no logic to it beyond appeasing normal mode raiders who think that some arbitrary gap release gives them a "chance" to see the content first.
Realistically, as everyone fully expects normal to be beaten in week 1 - every raider has a "chance" to see it before LFR goes live and therefore this delay is only really giving that "chance" to a larger group of people arbitrarily chosen at random who happen to be the players who can beat it in 4-6 weeks rather than one.
It's random and has no coherent logic and therefore shouldn't be subject to "middle ground".