All of your questions presume that the goal is known and achievable by both traditional and modern methods. I would posit that this may not be the case, and that the answer to your questions is very much dependent upon the outcome one wishes to achieve.
If one presumes that the goal of martial arts training is to learn to defend oneself, many roads will get you there. Some may get you there faster than others, and again, depending upon the person, since no two of us are the same. I would be willing to believe that many 'modern' martial arts would get a typical person to the point where they could effectively defend themselves in a shorter period of time, very generally speaking.
However, martial arts training covers a lot of territory. Not just in the methods but in the goals.
I study what I consider to be a traditional martial art, Isshinryu, an Okinawan form of karate. We practice many things that others find useless, including things you have described. Wearing a gi, bowing, learning some few Japanese terms for exercises and general courtesy, and so on. We do practice breathing control and basic body conditioning (nothing severe or damaging).
However, my personal goal has little to do with 'self-defense'. I assure you that I am reasonably good at defending myself (not great, but adequate), but if that is why I trained, I would have stopped long ago. I am a believer in karatedo, and the 'do' (pronounced 'dough') means 'way' or 'way of life' in Japanese. This is my path, and I will continue to walk it until I die.
It informs every aspect of my life, and it serves me like a conscience serves some people, like a guiding light, like a higher power, like a path to enlightenment. It's not a religion, I do not worship, nor do I serve. I just walk the path and let myself be instructed as I walk.
I should add that not everyone who studies my art or even in my dojo has the same goal I have. Some may do it for health, some for self-defense, some even for camaraderie. There's no one reason why anyone does anything, right? We all have our reasons, and none is necessarily better than any other. This is just what is right for me. It fits me like a hand in a glove.
Now, can a modern scientific martial art give me that? I doubt it. But horses for courses; I have no doubt many adepts in various modern arts could pummel me until my head rattled like a maraca.
If I wanted to learn to fight in the shortest time possible, I'd take up boxing. Those guys can rumble. And there are plenty of types of martial arts that can produce similar results.
If I wanted to learn to use a sword, I'd take up one of the several sword art styles of martial arts. If I wanted to learn to grapple, then Judo or BJJ or wrestling.
But I do not want to learn anything like that. I want to learn how to live my life in accordance with time and change, according to the principles of right and wrong, good and evil. I find that in the moving meditation of the art I study. You may not see my progress in my kata or how I handle a weapon. My progress is for me and how I live my life.
Traditional martial arts *can* but do not necessarily offer that. Modern arts devoted to effective self-defense provide what they claim to provide.
