I’ll start by responding to the question with my own belief. I would have to say that “personality disorders” or “abnormal behavior” in general are not a “problem” in the sense that there is something wrong with the individual. I would base that solely on the premise that persons or personalities are individual and are going to be different. The fact is we catagorize things and what is abnormal is what is not common, thus they are a danger to society and we label them disordered or abnormal. For instance, take a native living in the amazon and tell him to go live the capitalistic life. First, he wouldn’t be able to for obvious reasons, but his practices and his beliefs and behavior would be labeled abnormal and disturbed. Another example, polygamy. Other cultures allow for this as common practice. Set them in our society and there’s something wrong with them.
Now, to offer different perspectives. The first I’d have to state the psychological perspective. I already stated the basic idea behind that but we can look deeper into the biological basis for their determination of what is not “right”. Biologically speaking we have found these “chemical imbalances” which are the reason for “popping pills” to get that “quick fix”. Now I believe in science. It is great that if the chemicals aren’t being transmitted properly we can just take a pill and it’ll get it “back on course.” But let me refute this on evolutionary grounds. To keep from going in too deep, let me simply state that for there to be change, it must be allowed to persist! The fact we try to control and maintain everything how we want it and how we deem “fit” is, frankly, absurd. Let us go back in time to Heidlbergensis(sp?). How many of these ‘cave men’ were having chemical imbalances? The brain through our history went through a LOT of changes and rewiring (our brain is actually smaller than neandertal’s but because of ‘wiring’ we are able to have associations of objects, hence we get cave paintings with homosapien).
So on that, let me return to my original premise that each individual is different. Just as George Carlin said “the kid who eats too many marbels doesn’t grow up to have kids of his own,” let me say that the person with screwed up wiring who gets depressed and kills themself doesn’t grow up to have kids of their own! That may sound cold but we can’t deny the natural order of things and the fact that within any group or species things are adapting under their own methods and change (evolution) is occuring on an on-going basis. The fact is data shows that depression and such problems are on a rise and it is passed on by heredity. If people are incapable of surviving then they die off.
Now, on that perspective let me also state I am one of these “depressive” people. I have screwed up wiring plus it was also my social conditioning for me to have been depressed (and going through the crap I did in high school didn’t help). However, as I have seen in myself as well as helped in others and have seen others notice as well is that the “chemical imbalance” is hardly an excuse for anything. Unless you have lost touch with reality or have some kind of mental retardation that prohibits one from being able to “reason” for lack of a better term, then they are going to be able to introspect, adapt, and control within themselves their depressive or whatever “problematic” urges. I can go in depth to use examples of the un-limiting aspects of several “diseases” but I already know I’m rambling enough 
already touching on that evolutionary aspect let me move to a historical one to respond to the post some have made that “if you’ve seen them it is a disease.” Well, even in cases of schitzophrenia where the individual loses touch with reality, this has been a state that people have 1) sought to go after for religious reasons and 2) have been exalted as mystical experiences. To keep this short, let me just point out tribal shamans throughout history, when studied or observed by “lay man” we would say “they’re Fing nuts!” But to stay off the whole religious and shaman studies, these are very well organized and structured patterns and there’s even scientific data looking into shamanism. No, schitzos are not shamans, but are an example of people who are not in touch with reality. The main “problem” found in them is that they can’t function in our society because they can’t “reason” as we do in our catagorical sense percieved world, solely because they percieve things differently (of course we say our perceptions are best, but i’m not even going to argue that or am denying it). Just one more historical perspective though, look at the Oracles of Delphi who would go into bizarre trance states and wig out literally because they got high off of the toxic gas fumes that were coming out of the ground. They were said to talk to the gods. For all we know maybe they were! But the underlying fact is they lost touch with this reality and saw things different and were treated with great respect, not disgust.
So to recap, I have to say the effects, behavior, and individuals who we label as “personality disorderd” very well exist, but are they a disorder what should be of concern and I have to say no. We are individuals with our own personalities we’ve developed, through evolution, genetics, and how we socially and individual condition ourselves to adapt to whatever biology we have. The idea of the disturbed stems solely out of trying to find problems in what “doesn’t work” in our capitalistic “progress” and trying to correct the problems (thank you Skinner!). So if it isn’t obvious, I don’t like behavioral psychology
Just to note, I don’t deny that in our society these people who have these “problems” for lack of a better term will have trouble trying to live in our society. It’s a dog eat dog world here and they’ll get eaten up or be a danger to others. I think clinical psychology is important but I think being based off of behavioral science is not the way to go (personality psychology is the other alternative).
Just my 2 cents … or this would probably be like 5 bucks worth 