The life gain played by normal decks to sure up their matches against agro decks has to minimally impact the deck in their other match ups however in decks that are really abusing life as a resource such as Necropotence you typically need some life gain just to enable the continued use of your effects
In a time when Circle of Protection enchantments were rampant and several cards cared about the color of cards, changing the color of a spell in response was a legitimate strategy
As Nguyen put it: Black Panther, Wakandan king, as a white/green card that cares about lands, cares about creatures coming into play [was an effort to] represent the leadership of this character, the connection to the land, the connection to the super-valuable resource Vibranium
You or your opponent can look in both discard piles at any time you want
Its less about balance and more about showcasing whats possible, serving as a reminder of how far the Pokmon TCG has come since its early days
Having Vigilance is definitely a nice addition, though