Are Midnight addons mandatory for gameplay?

Addons in World of Warcraf are completely optional. The game is fully playable without them, as Blizzard designs all encounters, dungeons, raids, and leveling experiences to be completed with the base UI. However, addons can enhance your gameplay experience by providing extra convenience, customization, or quality-of-life improvements.

What are some of the best addons not available in WoW Midnight?

There were many addons affected, mainly ability-dependent ones, that were banned in Midnight. The main perpetrators on this list were DBM (Deadly Boss Mods), WeakAuras, and Details. Many addons of this type were either heavily limited or effectively made obsolete due to changes in the new WoW interface.