As a previous poster said, the value is individual to the person.

For me (and many others), F travel is there for a treat, annually or less often. I suspect that's where the OP is coming from too.

I have planned an upcoming trip next year, LHR-ORD in F, and SFO-LHR in J. I've done it that way around because on a daytime flight I'll be awake for the whole time, able to try some of the wines and have a relaxed meal service or two. I'll also be able to work through the IFE and take breakfast in the CCR.

On a night flight the priority is to sleep well - six hours or more, hopefully. That leaves only a few hours left to enjoy the ambience. What's the point of shelling out the extra Avios for F when a flat bed in J will do?

There are those who travel in F more regularly who see F as simply a more efficient or luxurious way of getting their head down, and the value between day and night time flights is less pronounced.

It all depends on your perspective and what you'd like to get out of the experience.