Theme Updates vs Changelogs vs Unneeded Plugins:

What if a Theme's developer adds functions or features to his/her product that end users previously had to install a plugin to facilitate?

If Easy Access to a Changelog doesn't exist, the end user may continue to use an unnecessary plugin unaware that the theme itself now provides the desired function or feature.

The end result may be plugin conflict with the updated Theme, or just duplication of code.