Personally, I like and prefer gentler methods of trainings such as yoga (depends on the type but usually it is gentle), Pilates, feldenkrais, Alexander technique, biomechanics, etc., than harsh ones like kalaripayattu, grotowski, suzuki, etc.
I find it more effective for myself. And the results are subtle and amazing too. That's not to say that harsher methods aren't necessary. They are and I would do them but minimally for a week's training. I like my body to find its way of getting better rather than being forced to.
Having done yoga and some Pilates before I find that my body looks and feels better after a week of practice. It dips and goes up again for the next. Plateau for a week, or few, then go up exponentially. It was better than gymming (and healthier too as I'm not using external weight to work my body) and more fun. The real attraction is in the results I reaped. I feel so good, stronger, is actually leaner and more confident. Of course diet plays a considerably big part too but that was a natural progression and not something I have to coerce myself to doing. And it definitely works for the actor's body. Most celebrities are said to do yoga and Pilates. (I also think they do other form of exercises.) But that's maybe for screen actors. The difference is that a stage actor's body has to be more alive and not just the top half or the head. The good thing about these harsh trainings is that after it forces the body to wake up, the body can remain awake without having to put much thought to remind it. I feel this when I'm on stage. It thus allows me to focus on other acting things such as delivery, actions, etc. That's about as good as what I think harsh methods is for. The gentler methods get supplemented and now let's the body find its grace, elegance and confidence when working (or even in everyday setting). But even without the harsh methods I think the body and mind will eventually figure itself out (if the actor is smart enough). We are lucky to be in drama school where such connection is force to expedite. But that's my speculation.
I am all for beauty, grace and elegance. After trying out an exercise of the feldenkrais and Alexander technique I feel my body as alive as doing the harsh methods but without the pain. It was invigorating! And its more graceful and aware of its surroundings (this awareness could also be attributed to my 6 months training of kalaripayattu so far). That's when I am positive it is not that necessary to have such harsh methods of trainings. The harsh methods also help in being grounded but that's kind of what Taiji does too.