Of course, having a central health database represent a huge leap forward for the efficiency and effectiveness of medical care. No more filling out redundant paperwork every time you visit an office, stuff you can't possibly recall 100% accurately. Any pharmacist would know what other drugs you're on, docs could see your entire medical history at a glance, etc. Massive cost reductions in eliminating the silo personal information, and improvements in care by making relevant information readily available to health care providers.
But why should google be able to use that info for targeted ads? AETNA lets you send your health history to a doctor before you show up, and HMO's have done very well, too.
It's the next step towards a health-based credit score IMO, and I'm against any private company running the database with no controls.
