There was a widely-circulated study a few years ago that showed that those policies result in
lower security.
The advantage of a forced reset is this: if your password has been stolen but not yet used, then you're locking the thief out.
The disadvantage is this: the greater password strength that is required and the more times someone has to come up with a new password, the more often they'll take shortcuts. Those shortcuts result in easier brute-force or heuristic attacks.
So if you look at the advantage, it's very small and potentially non-existent. It's rare to steal a password from a high-value target and then sit on it, especially for as long as a few months.
Looking at the disadvantage, it's actually very high, and it makes it easier to steal passwords in the first place.