Why did Summoner get Blizzard 2 when they already have a bind?

[Wolfenkritter]

A replacement for removing thunder to give Summoner's more AoE potential to piss Summoners off

Thunder was worth only about 5% (Maybe less) of your damage back then. It was only worth using with Contagion. When Contagion is down, its was hard to justify using it for its MP cost.