Presuming a company's financial health and that paying for F/J will not endanger that, the justifications are direct and indirect:

1. Ready to hit the ground running based on comfort (seat recline, lie flat, etc), less stresed due to quieter cabin.

2. Ability to work, including simply organizing thoughts.

3. Arrival to lounge/showers and the like (which may be important depending on time of day and ability to get to meetings).

4. Client willingness to pay directly or indirectly.

On the indirect front:

1. For people who travel a lot, it really matters. Anybody can survive any one lengthy flight, followed by meetings, followed by return. But, do this constantly and it takes a toll.

2. If you want top people and competitors for your top people pay for F/J and you don't, it's a negative. Doesn't mean that people leave over it, but it's a net negative. Perks matter and not worrying about F/J, car services, room service and the like, all counts toward job satisfaction.

But, as noted, money matters. There are tough choices to make in any operation and if F/J isn't sustainable, you have to bear the burden.