One thing I've noticed while studying Japanese is that I need to use a larger font size when reading Japanese than I do when I'm reading English. The characters are just too complex to differentiate at small font sizes. You can't easily distinguish a character with N horizontal lines without the character being 2N-1 pixels tall (one for each stroke, and another for the gap between strokes). There are common characters with as many as 8 horizontal strokes (The kanji for "kaku" for example, which conveniently means to write). Even today's video games (on nintendo DS, for example) have 11x11 pixel Japanese fonts that can be very difficult to read.
Any reduction in font sizes for readability must have separate standards for Asian characters, or the more complex ones will just appear as blobs.