A good argument against having it every day? In game, hardly any of the players joined the Bane, so they don't realistically have that much manpower. They should strike hard, but randomly and not every single day whilst trying to gather greater resources for the final battle for the throne...
Out of game? It'll get boring very quickly to have to fight it every day; at a rough guess, it looks like it runs for a calender day before deciding if the city is won or lost. As no one knows yet what the victory conditions are, that means people who want to aid their cause are fighting for hours... doing that every day until way after Christmas when the event is likely to progress to the next stage (as the staff will be back from vacation), when there's only one new mob to be seen, and they aren't doing anything but standing around in towns is going to sour people to the event very quickly. I don't particularly care personally about the loot; I'm fighting for the town not the katana or sash, but both the Bane humanoids and Bane Dragons have absolutely terrible default loot ... and it's a simple fact of human nature that you're not going to get many people grind them for weeks, not when there's no way to see that such material Humility is helping. Even if you fight around the town crier, he only has maybe 4 updates to share (you're winning, you're losing, you've won!) and over a day hearing them again and again is not very encouraging...
