Because from the way you write I see that you still haven't read on power. Not understanding what power is when talking about sociology is like writing a physics paper saying that some balls have a "propensity" to climb inclined planes and neglect to mention the force applied to them because you don't know what force is.

Let me start explaining this, but please read about it, because I have no intention of teaching sociology 101 here. Power can sometimes be compared to a force and sometimes to potential energy, but the best analogy, IMO, is a force field. There are different kinds of force fields (e.g. EM and gravitational) and they affect you differently based on different properties (like mass and charge). But each of us emits power and is under the influence of power all the time (and different kinds). It is possible, however, to attain more power (or lose some), often by aligning with others (you can think of it a bit like unaligned magnetic bits vs. aligned ones -- they could either cancel each other out or strengthen one another). In the end, all power -- like force -- translates to influence, i.e. moving people in a certain direction.

Now, I don't think there's a good physics analogy for this, but people who have more power, are much less influenced by others' power (maybe it's like momentum?), while those that have little power are basically heavily influenced and directed by the power surrounding them. What's more crucial is that power can prevent alignment and thus ensure that some people (often groups) don't gain more power (no physics analogy here). And what I'm saying isn't theoretical: those processes have been studied at length by psychologists, sociologists and anthropologists.

When you say that blacks and white are "different", but the differences -- all of them -- correspond with less power (power can be intelligence, it can be money it can be other kinds of things), you are basically saying that blacks are inherently less powerful on many power axes (and never more powerful on any of them).

Now, power is what defines social ranking (when someone has a higher social rank than another, that's simply other words for saying he has more power), so when you say blacks inherently lack power, you are basically saying that blacks are inherently socially inferior to whites and therefore "belong" on lower social ranking.

To this you will say, "less power in our society, but maybe not in other kinds of society", but that means that whites have built a society, that by their very nature, blacks are destined to be ranked low socially. That is, of course, what is known as a racist society, but that's not even the truth of what's happening, because all this time I assumed the studies you referred to found effects that are anywhere near those seen in society, which is not the case. The data points to a different reality -- our reality -- where the forces in our society are aligned in such a way that it's very hard for blacks to increase their power, and this has absolutely nothing to do with innate properties. Of course, this, too is a racist society.

One thing beginners often get confused about is how power forms and works, and they imagine smoky rooms and powerful executives, and -- most importantly -- something resembling a nefarious conspiracy. That's not how it works. Power is subtle and constant and often invisible (to those untrained to see it). It rarely requires a conspiracy, and powerful groups are an emergent property.