That's right, yet you can assume that every creature in Magic has reasonable values for power, toughness and mana cost. Colors aside, every card in the search results could be easily added to your deck. Most Characters or Characterizations in TV Tropes TCG
won't provide values > 0 for all
stats. Assuming that the number of possible traits (age, gender, combat, love, scariness, funniness, ...) will be huge, decks making use of traits have to be dedicated to them. An action deck, for example, requires many combat characters. Plus, you can't know which traits your opponent focuses on, so "Put target character with funny < 3 on the bus" would be useless in your action deck with and without numbers (that's the reason why I also wanted to introduce trait classes). I don't know how you'd design Arcs, but I assume they are specific in terms of required tropes/traits/etc. to complete them. Drawing the necessary cards is hard enough, but if you need two "combat + 2" cards for an Arc or Trope that requires "combat 4", this could take forever.
Now as I'm thinking about it, there is another solution: Replacing "draw 1 card each turn" with "draw cards until you have a total of X each turn".