cards shine brightest when they amplify your decks natural flow
Whenever you pitch a creature, this card lets you pay extra to create a 4/4 zombie copy of it, turning what would normally be a cost into free value
Flash creatures either function as one-for-one removal spells (Hired Blade), as two-for-one removal spells (Sentinels of Glen Elendra is better at surviving combat than Ashcoat Bear), and as flexible curve-fillers (Cloaked Siren lets you hold up interaction and have a threat if you dont need to use it)
Black Market: Like Pitiless Plunderer, Black Market tracks creature deaths and gives you mana, but instead of a one time payout, this enchantment gives you mana each round
And similarly, if times or opinions change and a card on this list looks fine in casual play now, we can take it off
Regardless, I dont know that now is the time for more than 60 cards, but I do know that as the card pool expands, it gets easier and easier to find more spells of a similar power level, but no other lands are close to the power level of fetchlands, so the incentives to build to maximize the power of our lands over the power of our spells do increase in some way over time, which is to say that, even if its not right now, it could be someday, and getting there first might be the best way to truly break Modern.