The only comparable English equivalent to 2ch is Usenet which has been around well before the Internet. Usenet has threads for almost every subject imaginable. Same goes for 2ch.
In comparison, 4ch still has very few categories and threads. Perhaps it reflects the number of people who come here. This condition alone will not attract the numbers you might like.
And most importantly, 4ch is not famous and has nothing to make it famous. It is not notorious like 2ch. It is not as diverse as Usenet nor Yahoo/Google Groups. What special or unique thing does 4ch have which would appeal to the masses? I see no such thing. There is no word-of-mouth buzz.
If you think the secret to 2ch's success was the BBS software, you are dead wrong. I'm guessing that whoever started 4ch thought (or hoped) that using the same software would result in the same popularity as 2ch. That was not to be.
There are many more factors and variables at work than just a piece of software for making a super popular site/forum/BBS. The college kid who started 2ch probably had no idea how wildly successful his project would become. He happened to do something at the right time and right place. His unique idea caught on and one thing led to another and it snowballed to what it is today.
Being unique and being the first one to do it is one key to success. The copycat will never attain the same success as the original inventor of a successful venture/formula. (One exception is General Electric, started by Thomas Edison, which is all but buried by Japanese makers.)
2ch's massive success is really unique. You can't duplicate it. Look at the Windows OS, eBay, PayPal, Yahoo Japan Auctions, Microsoft Word/Excel, Google, YouTube, Skype, and the iPod. All of them are enormously successful and they all have copycat ventures like Linux, Google Video, Zune, etc. None of these copycats have attained the same success as their original inventors. And they never will.
4ch is destined to be a niche thing, instead of a massively popular board. You all might as well accept this reality. One good thing about 4ch is that, for gaijin who wanna try and understand how 2ch works, they can come here first and see everything in English. After they understand how 4ch works, it makes it much easier to understand 2ch's system.