The smaller the House, relative to the total population, the greater is the risk of unethical collusion or myopic groupthink. In contrast “Numerous bodies … are less subject to venality and corruption”. [James Madison, 14-August-1789]
I would add another one. Right now, many of are laws are written by the executive branch through regulations. This is a direct violation of the constitution, and the civil servants who write these regulations are unelected and due to civil service laws can not be fired nor motivated (they get promotions and pay raises regardless of the quality of their effort). Such a change would most likely increase the democratic nature of the laws and regulations that guide our lives.