As I remember, that was before the rise of multi-platform, web-based and mobile apps.

You'd get Office 2003 and it'd follow the Windows XP style with lots of blue [1] and you'd get Office 2004 for Mac with the brushed metal styling [2] - and many applications only targeted a single platform.

Whereas in the modern age you get Slack for Web, Slack for Windows, Slack for Mac, Slack for Linux, Slack for iOS and Slack for Android - and it tries to be consistent across different platforms, instead of being consistent with different platforms.

[1] https://en.wikipedia.org/wiki/Microsoft_Office_2003 [2] https://en.wikipedia.org/wiki/Microsoft_Office_2004_for_Mac