Given how compact and complex and many kanji are, is it necessary for Japanese readers to have a much larger font on their screen? Can you make out complex kanji at the same font size/zoom level as Latin characters?
Kanji are shown at regular text size, even if that means that they become an almost unrecognizable smudge. As an example, take this button from a Japanese website that sells books:
It's an image, so visitors can't make the text sharper by zooming in. In cases like these, you just have to look really closely and guess if necessary.