I think for games built around a single-player story it's fine to have a reasonable estimate on how long a typical run will take. The problem is that both developers and normalfag casual audiences convince themselves that a longer runtime = more value for money, so you end up with hours upon hours of mindless padding where the "gameplay" is just looking at the map and going to the waypoint to tick a box, then repeating that a hundred more times. It makes the initial run feel repetitive and makes the prospect of replaying the game at a later date less appealing, so over the course of a few years you actually spend less time playing the AAA twenty-hour game once than the replayable six-hour game several times.