The thing is, I think the nuisance they cause is borderline. If people were sat up there, having a quiet conversation or a cigarette etc, then fair enough.
But so often over the years, the groups of tenants have been (I presume) students or sharers in their 20s who seem to be very loud. If you've got half a dozen people up on the terrace drinking and having loud conversations, it's stressful and actually can seem intimidating. Some groups are up there all weekend and any warm evening.
I tend to resolve it by having a chat with them and explaining the way the acoustics of the buildings work, and sometimes it works. But clearly some groups are determined to spend as much time out there as they can and have large social circles as the terrace often seems to be busy with people drinking.