Business class on long haul- pricing and seat choice

For the first time I’ve gotten an airline to the point where I’m doing missions from SE Asia to Western Europe. I may start trans-Pacific soon too.

In the early days when building a strong domestic network with a few ‘trunk routes’ up to 2 flight per hour all day on some 2 hour hops I have had the following cabin seats:

Business: Recliner short haul
Economy: Leisure plus (or less)

One Rec SH take the space of approximately 1.4 Leisure Plus seat. It is easy, without any connections in the domestic market, to charge way over 1.4 time the prince of an economy seat for a business class one. This means that premium heavy configurations were great in the early days before saturation as the margin on business was much greater than economy.

Now I am doing 10 hour missions I have the following:

Business: Full Bed Wide
Economy: Comfort

A FBW take about 4.2x as much space as a Comfort seat. However, there is no way I can charge 4.2x (and I’d need to charge more than that to cover the additional service profile cost too) the price of an economy seat or a business seat on this mission. Even with a relatively modestly sized business cabin for just 25 seats compared with 200 economy seats, the business class just doesn’t fill up on many routes at a little over 2x the economy price.

Even where the business cabin does sell out, the margin is a fraction of the economy margin. And I believe I would be better having a fully economy cabin as it’s margin is higher.

So this leads me to my question:

Is having a business cabin worth it on LH flights where the seats are 4x or more the size of economy and hence need 4x the fare to justify (assuming the economy seats would still be sold in an all econ cabin, which I believe they would).

What am I missing that makes business worthwhile, and more profitable than Economy on LH flights?