A primary benefit of a bicameral system is the way it demands careful consideration and deliberate action on the part of the legislators. A primary drawback is that it is tougher overall to pass legislation and makes it extremely difficult to push through large-scale reforms.
The executive and legislative branches complement and check each other. The purpose of dividing their roles is to prevent either from becoming too powerful. As a result, when one branch assumes more power, it necessarily assumes that power from the other branch.
Incumbents chase off would-be challengers because they are able to raise more money given that people want to back a winner and that voters know incumbents by name because they won the office in a previous election. The challengers who do take on incumbents typically lose soundly for the same reasons.
The peaks of congressional approval ratings have each occurred when the United States began military involvements overseas. This suggests that the start of a foreign war is one of the few things that triggers a positive reevaluation of Congress.