You probably don't know this, but the recruitment of one person for a clinical trial costs about $4000 and every year more people are needed per trial. A typical vaccine for example need about 40.000 subjects before it can be submitted for approval by the FDA or the EMA. Imagine the costs associated with clinical studies. So, many pharmaceutical companies recruit globally, especially in low wage regions.
Another factor is that many studies (for e.g. gene therapy) need to rule out genotypical effects, which basically means that test subjects or patients need to come from different parts of the world.
So yes, there are plenty of reasons why this app should in the future be opened up to the rest of the world.
Lol, you guys all sound like Apple announced "we don't plan on ever bringing this out anywhere else".
You sound ridiculous. OF COURSE, like iTunes Match, Apple Pay, and every single other service I can think of that they've made... it will expand to other countries as soon as possible.
If they waited until it could drop everywhere in the world simultaneously, it wouldn't come out for ten more years. That would please you???