I'll open with a (perhaps the only) positive - Good on Apple for releasing the ResearchKit as open source. That said, there are still a LOT of barriers here.
First of all, while ResearchKit is open source, it is still predicated on iPhone sensors and the like, so in this way it is proprietary. Now, perhaps with time and effort it can be expanded to allow the same sort of thing to be done on Android devices, but as of right now it is effectively proprietary. However, this leads into a bigger issue: Standardization AND privacy for health data and metrics.
Right now we have a horrible platform when it comes to medical data and privacy. Despite HIPAA and the mandate to move to electronic medical records, these were horrible half measures that in many ways did more harm than good by not being specific enough. For instance, the idea between EMRs was that any doctor, hospital, pharmacy etc.. should be able to transfer and use data from any other. HA! Fat chance. Why? Because of our old friend that has fouled up accessible quality medical care for years - the unregulated profit motive, and its friend: proprietary lockdown!
EMR systems, even for a small office based practice, cost hundreds of thousands of dollars. We're talking millions for hospitals or other larger centers or networks. And yet, they're all horribly modular and insular. Each EMR has their own proprietary data formats which are incompatible with modules from most other EMRs...or at best, require an expensive format-shifting module. For many physicians, EMRs are more trouble, not less - as they have to deal with tons of incompatible formats and halfassed implementations. I don't even want to get into the ICD-9 > ICD-10 > ICD-11 shift... All these systems do for now is leech money from providers and create a cottage industry of training, upgrades, and modules to sell. It does not improve patient care; at times it can be a threat to it.
The only proper solution will take an act of Congress, sadly. To require a single, completely open, unencumbered, universal, extensible, privacy respecting/encrypted, format for electronic medical records (and all facets thereof, from scheduling, to patient information, notes, etc..) - and then stipulate that all public insurance programs (ie Medicare etc..) will ONLY accept said format. Thus, you can use any EMR provider that you want, but they will all support the universal OpenEMR format. This is the only way to bring the original impetus behind switching to EMRs to fruition. I'd love to see the government mandate that the formats of GNU Health ( https://health.gnu.org/ ), the Free Software EMR would be used as a baseline for required standardization, as well as using a solution used GnuPG to help encrypt said records (patients have public and private keys as do physicians/practitioners, allowing complete control and traceability who has access to protected health info, who's making changes, and when). Until then, we shouldn't expect Apple or anyone else to have a myriad of applications that monitor and ostensibly involve themselves in the patient's health, yet report unknown and unknowable amounts of data in random forms to all sorts of individuals and somehow consider them to be in the best interest of the patient.
The other half of this equation is privacy; sadly something it seems we're losing more and more each day. Patient health data is already hugely mined and monetized; your pharmacy is selling your data to insurance companies and pharmaceutical companies. These same industries are buying your browsing habits and what you search, to try to figure who has X condition that will cost them money. The amount of privacy that a user can give up more or less unknowingly (or cryptically hidden behind innocuous seeming requests and permissions) simply by installing an application for iOS/Android is enormous - expanding this to health any further is a nauseating prospect in my mind. Lets not forget that even when some big name medical center puts their name on an app, they're using all sorts of middleware and third parties (including Apple themselves) to pass that data along, or even to write and manage the updating of the app for them, all of which must be "trusted" not do to the more profitable thing. Some will say "but HIPAA protections...!" Well, consider how many health-monitoring apps today get around those - they are not considered to generate "protected health information".
Simply put, we have bigger problems to deal with first, when it comes to technological healthcare intervention and failure to do so is at the peril of one's privacy and healthcare efficiency and effectiveness. The idea behind ResearchKit, if it wasn't so Apple focused, is good - but the current climate in which it operates is a dangerous swamp. We need a properly reformed healthful environment, conducive to best practices for patient care and privacy. Convenience is important, but it cannot take precedent over the aforementioned.