Since the plugin directory is being upgraded in the near future, maybe we could get new designations for plugin usecases.

1) Ordinary standalone plugins,
2) add-on/extension type plugins and
3) framework/helper plugins.

Imagine being able to pull up a list of popular frameworks. Or easily finding all available plugins that work with a particular parent plugin or theme.

Addon plugins also clutter up and confuse searchers. If you search for a forms or caching plugin and you get a bunch of add-ons mixed in the results it makes finding things harder.

I think the easiest solution is to create a separate search&index for different types of plugins. This clears up the unexpected results users get when their search intent is a standalone solution.