The current voting system America uses has yielded results time and time again that give the largest party a super majority in power and give the smaller parties practically no power or voice in government. It has also created "tactical voting" in which a voter doesn't vote for who they actually want, but for the other person who has a better chance of beating the person they don't want.
With a proportional voting system, such as the"single transferable vote" or "mixed member proportional representation," voters can more confidently vote on candidates they want, knowing that their vote will count more in the long run. It will also give smaller or minority parties the proper amount of representation for their voters.
The process will be more complex, but well worth it for American voters