ADHD is already too easily diagnosable IMHO based on the DSM criteria. The DSM V criteria will make it even easier to diagnose.
This brings up something I've been thinking about a lot. I think we do a really bad job talking about diagnosis and severity as two different things. I think this also fuels a lot of the discussions about misdiagnosis of bipolar disorder in youth.
We as psychiatrists make the decision about the diagnosis, and so whether we call someone ADHD or Bipolar Disorder or MonkeyBrained NOS is our attempt to be able to talk about our patients in consistent ways. These diagnoses also inform us regarding how we should treat. They do not necessarily completely inform us about how we should treat.
And I think that's where severity comes in as a different argument. It really isn't important (or, it doesn't have to be important clinically--it's clearly important on some level, but not in the way that's being implied here) how "easy" or "hard" it is to diagnose ADHD. The important thing should still be the level of dysfunction and suffering. An adult might "have ADHD," but that doesn't mean you HAVE to prescribe a stimulant (OR ANYTHING) if in your clinical judgment severity does not warrant it. It may be useful in identifying difficulties they are having, and it might reinforce their need for psychosocial interventions, even if that's just buying a planner to keep up with appointments.
I think that's where we've tripped up with bipolar disorder in kids (a very real, disabling illness) in that some assign the diagnosis in the absence of discrete periods of manic symptoms which are a distinct change from baseline. Otherwise, those children would probably get diagnoses of ADHD, ODD, MDD, maybe PTSD. Now those kids might get a diagnosis of DMDD, which is another argument I don't want to get into here. They didn't become different kids just because the alphabet soup on Axis 1 changed. I'm pretty sure the reason why the bipolar diagnosis gets assigned is because clinicians treat it as an indicator of severity. "This kid can't possibly have just MDD, ODD, and ADHD! He's way more impaired than that! He must have bipolar disorder! He needs Risperdal!" But really, maybe he just has severe MDD, ODD (or CD), ADHD, anxiety, PTSD, etc. And Risperdal may be an entirely appropriate intervention in severe cases, regardless of whether there are discrete periods of manic symptoms which are a distinct change from baseline or not.
So, my argument would be that none of our clinical practices will change much, because our patients' level of suffering isn't going to change one way or another just because the APA puts out a new book/website. No parent is going to come into my office and say in 2014, "Well, doc, Johnny stares out the window and forgets his homework and can't sit still and the teacher says he had ADHD, but I didn't come see you because nobody really noticed it until he was 8 years old because he was in a Montessori school before, and I knew you couldn't treat him for ADHD until DSM5 came out." It just doesn't work that way.
So, it makes really good sense to condemn lazy, sloppy, unthoughtful practice. It makes good sense to condemn handing out scheduled substances like candy without proper risk/benefit calculus.
But it doesn't make sense to generically condemn adjusting criteria to better reflect currently available research. It doesn't make sense to generically condemn prescribing psychotropics to young children (obviously, this should be an incredibly rare thing, but many of us work at tertiary or quarternary care centers, where there are simply going to be some rare cases severe enough to warrant interventions that, if commonplace, would sound ludicrous).