The thing is, something doesn't have to be a science in the very narrow sense of the so-called hard sciences to be of some use. Data can still be collected and analyzed, and if anything technology has on many fronts only made the aims of sociology less idealistic than they've ever been. Some products of sociology, like social networking theory, are quite practically applicable.
Basically, in terms of determining causality, a field like sociology can go halfway. It can observe, but it is very, very difficult to do a sociological intervention, which means causality runs a higher chance of being under-determined. That being said, while association is not causation, it also isn't meaningless, and at least to some (admittedly much more limited) extent, associations within a great deal of data and a couple of simple heuristics can reveal causes to us. It can do so well enough that it would be a better use of our time to actually seek this information than to dismiss everything as chaos and not bother with social studies.
What you're really getting at is the fact that sociology is probably the highest order field with bothered classifying as a so-called field (competes with its close relative, anthropology). This means a ton of variables, and a ton of variables means more imperfect information, and more imperfect information means it is less deterministic. But there is a difference between true randomness and probability. I personally think the universe is probably deterministic, and apparent probability is only ever the result of incomplete information, which means nothing is actually truly random and so nothing is incapable of being potentially determined. This means even in sociology the data we take in isn't going to be mere noise, and treating it as such is a sort of willful ignorance.
There's some very interesting ventures into applying the sort of math typically found in quantum-mechanics to human behavior. There are some in the field who are arguing that it is more useful. Perhaps you should look into it.
I think the social studies are full of hucksters, particularly the field of economics, but I don't think that's because the field itself is impossible. It's the people and a culture that has unfortunately emerged amongst those particular academics. It's happened to even the most deterministic of sciences at times.