Problem is, you just listed the 4 best talents in the game.
You shouldn't really think of Glass Cannon or Leech as a baseline for what talents should be. Both of them are ridiculously overpowered. Instead, think about Politician (-1 int, +2 charisma) or Far Out Man (+2 range on spells) or Zombie (heal from poison but die from normal healing).
90% of the existing talents are small buffs, or tradeoffs that specialize you.
