I agree there's a benefit to exactness. I don't personally think that benefit extends to fighting application, but I've too little experience with traditional forms practice outside NGA to make a strong case.I think the attention to detail is an important aspect of the forms in Taekwondo. The specifics are to reinforce the mechanics and concepts taught by the form. The requirement to match exactly means you must spend time training.
Even if it's not a 1:1 for fighting capability, training exaggerated stances and motions helps build muscle memory. People tend to shorten up their techniques in an actual fight, so the idea is that you train for those details in your forms, and then in a real situation it comes out in a more practical manner.