A 2 class 77W is scheduled daily, 3 class a/c may have been operated a lot but this doesn't bring the load factor up as EK sell it as a 428 seater 2-class a/c every day and a load factor of 69.64% is what they in particular will look at; it's still a relatively good figure, just not 77.4.
With regards to selling First Class, I would imagine this would need more crew, better meals with lots of choice (EK's F menu seems to be huge) along with other benefits which and if only say 1 or 2 passengers a day book it then it probably isn't worth it.