Because Modern is where the new players enter since that's the latest set they can buy. To attract more players through the creation of a better competitive environment, Modern is much better than Wild.
I am not anti-bot form of play. I am for a pro-human vs human form of play. And creating these human competitive environments where people's minds are used is a way that we can both bring in new players and also activate old players that did not want to bot in order to compete.