Frankly, I think the case could be made that the balanced budget contributed to economic prosperity (less gubmint spending). But, the point is that balancing the budget was a conservative goal which x42 glommed onto as a part of his "centrist" marketing scheme. Remember him parroting this phrase over and over and over again during the campaign, "...it's paid for in my balanaced budget"?
I agree with your point that an efficient government is good for the economy, but a balanced budget is an effect, not a cause. Now the Dems are saying that a balanced budget is necessary for a growing economy, or even worse, saying a government surplus is necessary. Surpluses take money out of the private sector, and are eventually used to make the government bigger and more wasteful.