Yes, badges are very much meant to come as a nice surprise:
Some of the badges are supposed to be surprises, not World of Warcraft style level grinds based on numbers.
I worry that if we provide too many metrics:
- it becomes noise, like a bunch of inscrutable F-16 cockpit gauges -- how are all these numbers useful except for these specific badges?
- the badge becomes the explicit goal instead of the desired behavior
- the badges are no longer a pleasant surprise and reward but an expected "level up"
As someone who actually happens to have Archaelogist, I know it did come as a surprise to me. When I got it I wasn't even aware of its existence and had to look up what it even meant.
There are only so many posts on this site anyway. And only so many of them stay inactive for long. And 100 is a big number. If the system constantly reminded everyone of their progress towards the badge, everyone would be actively grinding for it, meaning that no one would get it for years to come because we'd be stepping on each other's toes. (Case in point: the review queues.)