The concept of "staleness" encourages change for the sake of change, and I don't get it. Please ask non-designers if they want the look of their favourite software to be re-imagined.
The feedback to this is predictably similar to the transition from Skype 2.8 to Skype 5 (OS X), and I know people who still cling to their Skype 2.8 binary.
When something looks the same as it did years ago, while the entirety of the OS is being updated, not to mention design trends are changing, "stale" is a valid description. It's not "change for the sake of change" it's change for the sake of keeping up with the newest cool design trend.
Average consumers will choose a nicely designed app over one that looks dated, especially if they offer the same functionality.
But OS X does look the same as it did years ago, unlike Windows which went through five looks (2000, XP, Vista, 7, 8). It's not as if Adium has any design elements that could possibly age - it's a standard OS window with a customisable HTML message list.
Edit: I just realised that I have hidden the ugly message window toolbar. I'm not sure if it aged though - I already hated it on OS X 10.4 (when I disabled and then forgot about it).
The concept of "staleness" encourages change for the sake of change, and I don't get it. Please ask non-designers if they want the look of their favourite software to be re-imagined.
The feedback to this is predictably similar to the transition from Skype 2.8 to Skype 5 (OS X), and I know people who still cling to their Skype 2.8 binary.