That approach works for free command-line tools written for technology specialists.

But not if you are trying to make money with an app for the "general public", for example on the mobile app stores or oldschool shareware. Keeping it working is not enough, it must keep up with the latest trends in design and APIs that become available for extra features.

The old APIs and design guidelines could be a perfectly precise standard that still works - but it's the old standard when users expect new ones.