We can and have improved things massively. What we cannot do is fix everything at one time. The most we can realistically hope for is marginal improvement. Demanding perfection or nothing results in us sliding backwards.
But look at 60 years ago. Racial discrimination wasn't only legal, but state-mandated in much of the country. Interracial marriage was illegal. Being homosexual was illegal. A woman could be fired for not sleeping with her boss or for becoming pregnant. Businesses couldn't operate on Sundays because it competed with church. Firearms could be purchased by anyone without a background check at any store. Politicians openly ran on the platform that the white race was superior. Poor kids and minorities were drafted and forced to fight in useless wars while rich people could get college deferments.
We're so, so much better today than we were then. I don't want to rant forever, so let's focus on one issue and go even more recent:
30 years ago the general public was so homophobic that a Democratic President signed a law banning openly gay people from serving in the military. Clinton then followed it up by signing the Defense of Marriage Act barring federal recognition of same-sex marriage and allowing states to refuse to recognize marriages granted by another state - even though no states allowed it at the time.
20 years ago gay marriage was still illegal in all 50 states (next Friday is actually the 20th anniversary of gay marriage in Massachusetts!). It wasn't until 2012 that the first states legalized gay marriage through popular votes.
It's been less than 10 years since gay marriage was legalized nationwide.
In 2010 the majority of the country was opposed to gay marriage. Today nearly 80 percent supports it. That's remarkable.
We've improved so much very, very quickly. It's just hard to see when there's so much more work to be done.
But it took work to make the progress we have. If we'd given up and simply chosen not to vote we'd have empowered those who fought change.