The main issue according to the VC website (union) is the right to retire at 55. Their standpoint is that this is effectively cost neutral as the older pilots cost more and replacement pilots start at the bottom of the pay scale so cost less. They go on to say that this is already paid for, so is already in the pension pot. At first sight this argument seems to have some merit.
However so far I have not seen any concrete numbers. The counter argument would be that as life expectancy increases and investment returns decrease most pension funds and indeed state pension schemes are facing huge deficits. I confess I do not know the details of the LH scheme's funding. But I would be amazed if it is does not face some of these issues.
Lufthansa shut down the network for three days and anounced a strike cost in the tens of millions. But they have said they do not intend to make a better offer. The suspicion must be that LH management have picked where they want to fight.