As I write this, the ranking of the comments here is... strange. Those who see this as being yet another way of Google using their power to manipulate what people see on the Internet are being heavily downvoted, while those agreeing with the practice are not? That doesn't feel like HN to me.
I'm in the former group. This mollycoddling is just going to lead to more users who can't decide for themselves whether something is suspicious or not and are thus easier to deceive, which might be exactly what Google wants, but I certainly do not think it is good for the Web as a whole (or even society in general.) Being able to make these sorts of decisions of trust is an important part of growing up in general, and I'd even say "finding the right download button" could be considered a sort of right of passage to being an effective user of the Web, and not just a consumer.