Election day should not be turned into a national holiday because it's not clear that doing so would be an effective solution to increase voter turnout.
The argument for making election day a national holiday is that when voters have the entire day off, it will increase their turnout to the polls because they have the entire day to vote at their convenience. However, this argument does not seem to be entirely true. For instance, moving election day to the weekend has been something that many countries have adopted due to the same type of reasoning in regard to voter turnout. But in an analysis of voter turnout in other countries, it was determined that while countries with weekend voting do tend to have higher turnout than the US, adopting weekend voting hasn’t actually increased turnout within countries that have it. Looking at a country like Switzerland, despite weekend voting and the mailing of ballots to all citizens, it has the lowest voter turnout rate in the developed world at just 38.6%.
Thus, the convenience to vote is not the problem.
Increasing convenience and allowing people to have more time to vote will not be an effective solution to increase voter turnout. Even if registered voters have an entire day free from work or school, they still may choose not to show up at the polls.