Where modern karate goes wrong in self-defense is where fighting comes first.
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Street fighting and self-defense are two different things. Most people think about this as the same, even martial artists. They are not. In street fighting you are basically a fool that lets your ego expose you to danger. Street fighting is for people that believe they have something to prove to someone.
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Most people think self-defense is what you’ll find in most martial arts schools….. the reality is….. it falls far short.
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Self-defense is fighting for your life, or to protect someone you care about, or to get yourself out of the worst situation you find yourself in. Self-defense is ugly, dirty and scary, self-defense is the worst, or the last 30 seconds of your life.
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Self-defense is only a part of self-protection. Self-protection is above all a mental skillset. Situational awareness, tactical planning, understanding body language, assertive communication, etc, etc. Punching and kicking, is only for when your most important skills have already failed….. and they will fail if your training is 80-100% punching and kicking. What most places teach as “self-defense” is actually the worst of self-protection, if you are relying on dojo sparring/fighting to save your life.
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Most people still believe that what you see in combat sports is what will work in street fights or self-defense. What you see in combat sports is what works in combat sports, within their ruleset, with trained opponents, with the intention to score points or reach a winning conclusion. None of that applies to self-defense and very little would apply to a street fight.
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People still believe that a style, or school, or system will determine the winner of a fight, or they look for the “most powerful style” or “most effective martial art”. Its people and the skills they learn and develop that are effective, not martial arts. Training methods and principles determine the acquisition of skills, not traditions or linages.
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Stress inoculation training, mental training and live training put skills to the test and help you hone them. But you need to develop those skills first and you need to keep working on them afterwards. There’s no point in just sparring for the sake of it. Apart from that, sparring is not the only way to train with live energy, and sparring is not the same as stress inoculation training. Sparring is not the same as fighting, and fighting is not the same as surviving.
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“Winning” is defined by the situation, and the way “you win” will depend on that context. So standing toe-to-toe trying to hurt the other guy is not always the way to “win”, if that constitutes assault, or manslaughter, or if that means you’ll deal with his friends afterwards.
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You need to understand these differences, because the training, the tactics, the principles for each of those goals is very different. All the protective equipment in the world isn’t going to protect you if your training is in the wrong context. 
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