Single-seat districts are a fairly new custom in federal districts, and have led to problems with incumbents having an unhealthy advantage, especially since term limits do not currently exist for federal posts. Minorities have often been gerrymandered into less representative "majority-minority" districts, which leads to fewer seats to voice their interests. Most Americans are centrist, but our government has become more partisan, while voters outside of swing districts are largely ignored. Because we don't loudly demand candidates whose priority is fixing a rigged system, we get two flavors of the status quo on election day. Your vote is only truly wasted if you settle for the options given instead of standing up for truly representative government.
America is a large country. The ratio of citizens to representatives is close to 1 million to 1. To have a better ratio would require well over 5,000 representatives. This would likely be overly burdensome. Further, both parties are able to redraw districts, except in a few cases where independent commissions do this, to their own benefit. Without having to redraw districts every 10 years could save money and take away political corruption. Each state has at-large elections for the Senate, so we are familiar with this. This would be at-large for each state, with it population-based as it is now. We could use proportional representation for parties or ranked-choice for individuals.