Did we? I've not seen any statistics about how much faster the games got. Or more specifically, about how rare long games are. Because I don't think the people complaining were complaining about games taking 5 days when they wanted 3 days, I would think they were complaining about games taking months. Did those games go away?
Well, I never saw anyone complaining about too long games before the change either, but perhaps those complaints went through the chat when I wasn't there, or through JIRA when that was still active, or via email or whatever. Anyway, I have no insight into the relative amount of complaints.
Just to clarify: I don't want slower games. I usually finish ladder games quickly, sometimes within an hour if my opponent is online. What I want is a reasonable cap that allows unexpected life events to take you offline for a few days without immediately losing games. I think 7 days is reasonable, while with 3 days it is entirely possible for the unexpected to bite you.
The downside to auto-vacation is that it means that when someone stops playing on OGS altogether, it may still take more than a month for their games to time out. If people plan to be away for a week or more, they should just activate vacation.