So the wage I earned last year wasn't subject to inflation?
What your implying is money from investments are superior to money earned via labor and should be treated differently. I disagree, whether you make 100k from wages or 100k via investments it money earned.
You do realize why dividends are treated differently than other classes of income? Dividends are distributions of after-tax profits to shareholders. In order to minimize double taxation, the dividends are taxed at a lower rate.