First... It's because the class.. As created.. Is dumb. No.. Really.. Think about it. Any doubt the class is poorly thought out ends with the realization that a charisma based class has only bluff as a charisma based skill. Right.
To fix the sorc add all of the warlock class features except decieve item, fiendish resilience, and energy resistance.
The sorc carries a grimoire. This carries all of her spells known and is limited to the number of spells a sorcerer may know normally. To cast from her grimoire is a full round action.
She gains the hp, armor, and skills of the warlock. She retains her familiar.
To fix the sorc add all of the warlock class features except decieve item, fiendish resilience, and energy resistance.
The sorc carries a grimoire. This carries all of her spells known and is limited to the number of spells a sorcerer may know normally. To cast from her grimoire is a full round action.
She gains the hp, armor, and skills of the warlock. She retains her familiar.