Since the Banking act of 1933 came as a response to the foreclosing banks it withheld many restrictions. As the market began to show signs of stabilization the act was up for reinterpreting and were loosened. Since they were loosened, banks kept seeking more restrictions to be pulled off the bill. The constant reinterpretation of the bill would have caused the bill to become overall ineffective. Ultimately the bill would be repealed due to its uselessness.  Big banks and big business's were, in their views, affected negatively because they were income was sharply decreased by being forced into investment or commercial investment. 
This act was not in place earlier due to the fact that their was never an economic downturn of this scale. Back then when the economy dipped people knew that it would make it's way back up on its own. They had no reason to believe in 1929 it would be any different.