*beware, one man's opinion follows*
that question deserves another question, what does power mean for you?
much of our education have either implicitly or explicitly pushed us away from power, because "power tends to corrupt. absolute power corrupt absolutely." most of us can not trust ourselves with power and we do not trust those who have power or those who seek it. it has now becomes our social subconscious.
the search for internal strength (the physical kind, not the spiritual kind) has been going on for millenniums. before the invention of gun, where we still fought, in up close and personal, having the right kind of power was the different between life and death. how does a smaller and weaker person survives against stronger, faster, and more numerous? you trained for better fighting techniques, tactics, strategies, viciousness, deviousness, weaponries, and so on and so for. you find anything that would give you an edge over the other person. those who did not, had not the chance to pass on the knowledge, i.e. selective process to weed out the stuffs that didn't work. internal power in martial arts was one of the many edges.
power doesn't corrupt. we, human, are. throughout our history, many of the major changes happened because of some of the most vicious bastards we produced. most are very bad, but they were the catalyst for change. we hated them. we associated power with such as they. what we didn't realize, is that in each and everyone of us, there is a vicious animal lies dormant, only wait for the right condition to unleash. many of us aware of such animal, and shy away from it. if we admit such animal exist, then we admit that we are bad, which we cannot see or allow ourselves to be view as such. because, in our mind eyes, we cannot be bad.
so, the search for internal power in martial arts, for some are to continue the old tradition of survival; for other, dominion; other stills, scholar topic, fad, and other reasons that we try to tell ourselves.
i won't tell you my reason to seek it, because it's mine and mine alone, my beast (it's a chihuahua
btw, for those who think IS training is quick and easy, i can tell you now. you are absolutely wrong! it requires great dedication, pain and sweat, more than you can imagine. no quick and easy buck here.