All mods currently go under Mods, but letting players organise them into subfolders (like Mods/Content Packs) is a common request. Add a way to support that.

Proposed implementation:

• Folders with square brackets around the whole name (like [content packs]) will be treated as mod search folders, with the same logic as Mods. Only folders directly under Mods can be search folders (at least in the initial release).
• When the player has custom search folders, SMAPI will show a message like this:

  Searching for mods in Mods, Mods/[content packs]...

• When loose files are detected in a mod search path, SMAPI will show a message like this:

  Found files directly inside Mods/[content packs]. Each mod must be in its own subfolder.

The modder reaction to this was mixed; shelving in favour of more unanimous improvements.

Done in SMAPI 2.8 via #583.