Reading what other bloggers have to say, I notice a theme (here and here, for example) to the effect that the extremely negative view of autistic lives found on in some places, such as Cure Autism Now, is out of place.
By way of full disclosure, I'm in the neuro-diversity camp. The way I see it, no matter how our brains are wired, it's pretty odd to find our selves on this planet processing information and interacting with the environment. We are all, at the fundamental level, in the same boat. And to say that one way of processing and interacting is better than another would be like saying that it is better to be born a cat than a dog. So, that's my bias.
I also believe, however, that happiness is better than suffering, and that, for all conscious beings, happiness and suffering are a function of how we interact with our environment. From a biological perspective, that is why they exist -- in order to flexibly shape our interaction with the environment.
If we are unhappy, we can change the environment or we can change ourselves. I think that people who have an accepting view of autism have this view because we see ways in which we can change the environment (support, accommodations, technology, awareness) enough to make our children happy. We also see potential for changing our children (education, development) so that they can be happy even in unmodified, or minimally modified, environments. My guess is that parents who are less accepting of autism, may feel that way because they do not see any way to change the environment or change their children enough for them to be happy. If autism was making it impossible for my son to be happy, you can bet I would be much less accepting of it.
Of course, as soon as I start down this path, I run the risk of being seen as reducing it all to distinctions between high-functioning vs. low-functioning. But that is not my intention. What I am actually talking about is happy vs. unhappy. A person can be very "high-functioning" and still unhappy. The opposite is also true.
I'm not sure what the incidence of unhappiness in the autistic population is compared with the general population. What is more, if it is higher than that of the general population -- and I suspect it is -- I'm not sure how successful we can be in reducing it to normal levels. It is the answers to these questions that I think should determine the extent to which we view autism in the overall, and not just the autism that affects us personally, in a negative or accepting light.