While I think a shower is not essential, I think what is essential is a nice and large lavatory in F. A perfect example of this are the lavatories on QR's A380's in F.
The lavatories o nboard the EK 77W in F for example is just unacceptable.
I agree that a large lavatory is, in 2015, a requirement for F - but I'm not sure where you could fit two of them on a 77W in F, and to still have 8 seats!