Question about "Direct plugin installs (repos, URLs, local paths) are deprecated. " #2877

Recently (as of version 1.0.35-0 or so), I started getting this warning when running copilot plugin install /path/to/plugin/on/my/machine:

⚠️  Warning: Direct plugin installs (repos, URLs, local paths) are deprecated. Only plugin@marketplace installs will be supported in a future release.

Can anyone shed some light on why this change is being made? Also, will this affect the --plugin-dir CLI option too, meaning all custom plugins will have to come from marketplace, or will there always be some local source for custom agents, hooks, etc?