So, when do you think Larian will allow all druids to recast spells prior to wildshaping? Like call lightning and Moonbeam? It really hurts the class to be stuck without any spells, which is a core feature in tabletop.
Myrmidons also don’t benefit from proficiency bonus to attack rolls with their weapons, because Moon Druid doesn’t have proficiency with those weapons.
As for making Moon Druid competitive when compared to Sorlocks, Socradins, Lockadins or Sword Bards, just give them exclusive forms tied to items with variable costs. For example:
-Ring of Draconic Power (legendary, act 3 or late act 2). Allows the user to turn into a young red dragon. Uses 2 charges. Moon Druid exclusive
-Ring of Monstrous powers (Rare, act 2). Allows the user to turn into Bulette. Costs 1 charge for Moon Druid, 2 for non-Moon.
-Ring of corrupted vines (Rare, act 2). Shamblimg mound, look above.
Basically this gives Moon Druids exclusive forms, while giving them extra fluff.