You seem to have a fundamental misunderstanding with regards to what ResearchKit is about. It's not HealthKit, which is aimed at helping people to be healthier. It's ResearchKit, which is aimed at connecting medical researchers with voluntary subjects who are willing to submit anonymous data. As it is right now, researchers seeking data on how well a treatment affects a disease need to first seek out people with that disease, then they need to either bring those subjects into a doctor's office to be tested, which is typically done on an infrequent basis, or they need to rely on self-reporting out in the field. There are numerous flaws in those methodologies, leading to all sorts of lies, omissions, and other forms of error creeping in. And that's the best we've had to rely on up until now. Plus, response rates are ridiculously low since there's no great way to put researchers in touch with potential subjects, and even when potential subjects are aware of the research, most don't want to deal with the hassle.
By increasing awareness, taking the hassle out of it, and even promising to open source ResearchKit, Apple is providing a foundation on which researchers can finally address those issues. They're putting the diagnostic tools directly into our smart devices, and are doing so across any platform, thus allowing the researchers to get frequently-collected data from subjects under actual conditions, rather than having to rely on faulty self-reporting or infrequent lab visits. They can also get a much wider swath of data, allowing them to have more certainty about their results, along with a better understanding of what "normal" looks like. Even if a hypochondriac is using an app that relies on ResearchKit, it's a win for all of us, since it helps to establish more baseline readings from which we can better understand how our bodies are supposed to be behaving when we're in the real world, rather than in a lab. Moreover, it may eventually help to establish a baseline reading for them, which could then be used to show them that their readings are in line with where they were before when we knew they were well.
All of which is to say, this has nothing at all to do with people fretting about being sick, and has everything to do with helping research doctors better understand diseases and how the treatments they are providing address them. Joke about it if you want, but it sounds like a worthy goal to me.