This is only an outrage because of the size and success of the C3 church and the corresponding wealth of the man who built that success. The reality is that almost all non-denominational churches operate on the same tithe model. C3 just happens to be more successful at it than most churches. The average non-denominational church does not get criticized the same, because the pastor isn't living a visibly wealthy lifestyle like Phil here. However the same teaching about tithing is used to manipulate and guilt members into giving 10% of their income to pay for a building and people who make their living off preaching.
Tithing is not a new testament biblical teaching. Tithing is part of the Old Testament temple/priest system. The same system that Jesus preached against and abolished with the new covenant. The reason most Christian's cannot hear from God accurately themselves is because they are paying a priest or pastor to be the "go between" God and themselves. By following and accepting the terms of the old priestly system, were the priests were the only ones who could enter the presence of God, they are preventing themselves from hearing God for themselves and hindering their ability to enter the presence of God on their own.
By accepting the false teaching of tithing, Christians are metaphorically re-hanging the temple veil that was torn in two at the crucifixion of Christ.
Yes there are many "Pastors" who teach tithing to the church, but do not make themselves rich off it. But it still does not change the fact that tithing is part of the old temple/priest system that has been done away with.