It also plays an important role in Villager ranking. Berserkers need to cut down mobs quickly to offset the fact that unless there's a Defender around, they have no way to speed healing.

As for my personal opinion, I think mages are supposed to be fragile at low levels, and maybe low levels means sub 40. A price must be paid for the ability to pump invoker damage, duo + neuro, archons and devils, bad-ass forms, Undead and huge unholy weapons.

By the time you get to hero the staggering majority of Villagers are underpowered compared to the mages and that's the price they pay for dominating at the 25-40 range.

Disclaimer: I'm a serial Villager who thinks that Gary Gygax made the right decision to have wizards be weak until they had paid their dues.