Maybe as an initial set of training wheels. But it's the difference between law and grace. The law asks "What's the amount I am duty bound to give?" Paul says, "How much am I able to give in response to the love I have received?" You can't really get from the first question to the second; they are entirely different in kind.
Personally, I think if we are going to insist on tithing, we should also insist of the law of first dough (Num 15:18-21): whenever anyone in my congregation makes a loaf of bread (or a batch of brownies), the first piece must be given to the pastor.
For a fuller explanation of the tithe laws, and their relation to Christian giving (including general equity application), there's a handy little book here: