Elections are key way for citizens in a democracy to communicate with representatives. Different rules about elections and concentration of assembly power can create either majoritarian or proportional systems of democracy. Theoretically, we expect a tradeoff between majoritarian and proportional aspects of democracy. Empirically, both types of systems seem to do a relatively good job of achieving the goals for which they are designed. However, proportional systems seem to do a better job both representing diverse interests (based on committee power) and aligning government and policy makers with the median voter's ideal point.
What is responsiveness?
PR and majoritarian systems have a different view of the relation between voters and politicians. Majoritarianism encourages legislative mandates and the implementation of majority/plurality will (goal of accountability). Proportionalism is an attempt for policy to be responsive to as large a coalition as possible (goal of representation).
Role of elections