More storage is needed to makes skirmishers want to also do other things. Spedning 92 turns each day on skirmishing gives little left for other endeavours. If you plan something special which requires lots of turns for a period, you will not be able to use the skirmish points; they will simply be lost, since the storage capacity is only around three days worth of skirmish points.
So if someone is considering something with this limited skirmish storage, he has to consider not only if the action is profitable in itself, after all costs for voodoo, retaliatation and similar is accounted for - he must also take into account the value of the lost skirmish points. Simply put: If skirmish points can't be stored, a skirmisher may decide that it's simply better to just keep skirmishing, rather than participate in other activities too. And we want action, right? Things that happen? So increased skirmish point storage is a way to remove the incentive to only do skirmishing. This way, you can do other stuff for a couple days, and when things slow down, you can return to skirmishing, just doing a couple more each day. I fear that otherwise, we'll end up with several people doing nothing interesting, just skirmishing.