>>21 makes a good point. It's not that people in Japan are too afraid to make their own better 2ch, it's that 2ch WORKS. 4chan, like it or not (and I don't), is the Western equivalent to 2ch, so it's not like it's even possible to uproot something so well-established.

The issue most people have with 4chan, though, is that it sucks. Anybody who tries to make a better 4chan is destroyed because of three things (besides the above):

1. Very few people who go on 4chan know that boards exist outside of 4chan.
2. The majority of 4channers are socially inept nerds who can't possibly make a non-4chan board fun to post on.
3. People who make their own boards are generally said socially inept nerds, so they can't possibly have the skill to manage something as complex as that.

I'm sure 2channers know these things by now, which is why nobody has bothered to make a 2ch copy.