There are many ways to argue that political reforms are necessary (assuming that you are asking about the United States). Let us look at two.
First, we can argue that it is necessary to reform Congress, in particular, the Senate. In the Senate today, it is too easy and too common for a minority of Senators to block legislation. The need for 60 votes to get anything done gives any 40% of the Senators the power to block anything they like. This helps lead to gridlock.
Second, we can argue that it is necessary to reform the system of campaign finance. Today, groups can raise unlimited amounts of money (often without disclosing who donated the money) and use it to try to influence elections. It is possible to argue that reform is needed to reduce the ability of these groups to spend money on political ads and campaign contributions because it creates the impression that our politicans are for sale to the highest bidder.