****** warning some may be offended by this post ********
To be blunt to say wing chun doesn't have a hook punch or doesn't have this or that etc shows a lack of understanding of wing chun.
Wing chun forms are not rules. They do not contain all there is to the system. They do not set out the only way of doing things.
While everyone will say wing chun is conceptual not everyone understands what a concept is and what this means. There are several places in the forms where the hook concept may be seen and derived. Chum kui has no backward step. Does this mean you can never step backward? Of course the weapons have backward steps. Does this mean you can only step back after you have learned the weapons?
When 2 students asked Yip Man who was doing the correct tan sau his answer was both. A perfect tan sau that fails to stop a punch and you lose your teeth isn't so good. A horrible looking tan sau that stops the punch would be the perfect tan sau in the instance.
There are no set rules only concepts to be adopted to the situation.