Because most people accessed the internet on their clamshell phones and not through a PC/laptop. So most websites were designed to be mostly text and easily browsed from clamshell-phone internet browsers. Now that smartphones have become ubiquitous more sites are finally being designed to look nice on smartphones - sometimes still at the consequence of desktop use. It took a few years after the iPhone release (aka: for it to get widespread market adoption) for JP websites to start "catching up" with Western web design.

There are some other reasons too - but I'd wager the above is the #1 reason and others are more of an "in addition to that" type thing.

More info: https://randomwire.com/why-japanese-web-design-is-so-differe...

They're pretty decent now (apart from legacy) but it feels like 2004 lasted until about 2013 when it came to Japanese websites.

Someone somewhere said of content "let it breathe" and that got repeated until breathing content became a cargo cult. That cargo cult summoned the demons of flat design. They brought with them Metro, Material Design, Bootstrap 3, and iOS 7.

Content started breathing heavily, fonts got almost too skinny to read, and it's almost impossible to tell if text a button.

Makes sense to me. It looks cleaner, it's easier to read, and it's less confusing. If you have a ton of things, it gets confusing and overwhelming. Keep it simple. And stop with the tiny text damn it, there is no reason for it to be tiny. cough hackernews cough