Nobody is buying Talas Warrior to put in a deck, so selling it is extremely difficult compared to a card of high demand with a relatively equal price, like Mystic Remora
Being able to take out the smaller things and keep the bigger stuff about makes mass removal feel very one sided against the decks you have it in against
Sure, your opponent might have ten beasts in their green deck, but Callous Oppressor would still be able to steal their four goblins, three elves, and two other creatures that weren't beasts
Drawbacks that appear if you pay the life rather than the mana for a Phyrexian mana symbol could bring the mechanic into a more fun and stable design space for future sets
Join me next week when I I guess there's no point about getting cute, we all know it's the second part of my Pro Tour column
I need 2 white mana to cast just about anything in my deck