The better airline F meals are actually superior to 90% of the restaurant meals. And the best airline meals are so good that you would not blink an eye if you were served that same food, on the same china and even the same silverware at a restaurant and then charged USD 100 (US flights excluded).
It can be -- and sometimes is -- that good (thanks to high-tech galleys, freshly prepared food, skilled staff ... it isn't accidental and a big investment for the airline). Some airlines have it, and some don't.
Now your other question, why if F worth the hefty premium? On an ongoing basis (dozens of flights in F, eliminating the novelty or special event factor) I think there is only one reason: time. I save a day by flying F ... and for me that justifies the cost. Usually I fly overnight and am able to get a productive workday both before and after the flight; and do so for several flights in a row. This is impossible to do in J (not enough sleep, too much commotion, not enough flexibility). I do stay at the Peninsula (sometimes) but not for a week -- I can't afford the time. I am happy with the Oneworld airlines (AA/BA/CX/QF) though I wish they would equalize the quality (to the CX level). I am less happy with Star (LH/SQ/VS are good, the others are awful and worse) and with Skyteam (DL is good, the rest of the alliance is useless).