Because how will the game last without locking content (characters=content) behind large grind walls?
Also, it's not so bad if you hyper-focus on gold farming and keep your eyes on a singel character at a time, never spending gold on anything else or getting any character or faction points! Why, if you follow these steps, you can have the current (as of the time of posting this) roster unlocked after farming just shy of a cool 1 MILLION gold! I estimate that will take you only a cool 125 hours, give or take a little. It'll probably take more though, because you can't win every match!
And by the time you finish that, I bet all the other characters will be out by then, and who knows how many hours it'll take to farm them? And doesn't this all sound like game value to me?
Everyone knows that people quit playing a competitive co-op multiplayer once they have access to all characters and weapons, so you can rest easy to know that the low cost of this game will keep you playing for hundreds of hours grinding for that sweet, sweet gold. Talk about high value for a low price!