My guess is that they only do it because they got some pretty severe threats from the EU behind the scenes.
Not even behinds the scenes. The GDPR-rules that will be implemented by 25 May 2018 stipulates, among other thing, that any organization that collects or process data about EU citizens must get consent and inform the individual about what is collected and how it will be used.
The fine for non-compliance is up to 20,000,000 EUR or up to 4% of the annual worldwide turnover, whichever is higher. Not exactly peanuts.
A good guess is that this is a preparatory move to ensure that they are complying with this when it hits.