In this particular case with Safe Browsing APIs, there wasn't a 'surface area' in the way that you mean, to begin with. The article, and commenters, are incorrectly making it appear that way.
As long as you have a 'smart' phone, it will talk to servers. Messages, email, contact sync, online backups, tools to give you trace possibilitiies if your phone is stolen ... everything needs some kind of server. And if you use an iPhone, a lot of those will be located at apple. If you use an android phone, those servers will be located at google (and possibly also at the hardware vendor eg samsung etc)
Aside from the whole 'company A can be trusted more then company B' thing which is in my opinion a personal matter, this specific item where apple will route the traffic to a 3rd party through apple to hide the ip etc of their customers is a good thing.