They just engaged in an action that substantially increases their monopoly over access to user information, which is their golden goose. And this action is going to result in some degree of backlash. People hosting information only static sites aren't going to be thrilled that Google is effectively coercing them into, at the minimum, setting up let's encrypt when they have no reason to do so. And of course, this can be seen through some lens as benefiting the public good. Do you really think Occam's Razor points to the second reason as the primary incentive?

Another example from Google would be them preventing you from running plugins on Chrome that were not from the Google store. Yeah, it can be spun to be about protecting users from malicious plugins but it also enhances their control over their users. Incidentally, they decided to ban evil things like Youtube Downloaders from their store as well, which is a far more impactful given their increased level of control 'for your safety.'