One of the quirks of the Commander rules is that if a mana symbol appears in the casting cost or in the text box of a card, the color of that mana symbol contributes to the card's "color identity." So if you used Ishkanah, Grafwidow as your commander, you could include green or black cards in your deck
It can even be removed as a bonus
The main three ways I see creature Auras being made stronger are recursion (Rancor, Spirit Loop), replacement (Griffin Guide, Mantle of the Wolf), and protection (Diplomatic Immunity, Indestructibility)
They work together as a team
Fuwalos already has eight rarities and can still be hard to find even on the secondary market, while Purulia keeps creeping up despite have five printings of its own
More than just strong battlers, each one embodies a unique aesthetic and storytelling flair that sets them apart from previous starter trios