From a gameplay standpoint we needed something that's going to potentially bring new abilities to the game and allow older characters to be modernized. I don't think relics are a bad idea but of course coming at this stage in the game and introduced as g13 feature means one and only one thing: it's revenue generation.
This is why I'm scared of them, I know for a fact this is going to be a p2w thing, those who pay will get relics, those who don't will just have to grind it out and like most grinds in this game, we'll never be able to enjoy a variety of characters but we'll just have to cherry pick whoever is meta at the time and just have to forget about everyone else.
I don't think most of us will have the opportunity to enjoy most of these abilities even months or years after they come to the game, while others will just have them day 1. I wish greed was lesser with this one...