The thing is, most people, outside of US, think CNNI is actually the same CNN people in US get. In fact I used to think that too when I first became a regular viewer in the early 00s. So for most viewers CNNI is THE CNN , one and only, and it represents news from the US and from the US perspective, as oppose to BBC or Sky, for example.
This is why having another CNN would be more than confusing.
I agree, and I also want to point out that it works both ways. Most Americans seem to be unaware that CNN broadcasts internationally, or even if they think that it does, they think that it's the same version of CNN in the U.S.
As for the main topic, we've been over this many times on here. CNN has no interest in trying to pursue cable carriage of "niche" networks like CNNI or CNN/fn. It's difficult and time-consuming trying to get a channel added to a cable lineup in the U.S., and it's likely not worth the effort for how many viewers it would get, especially considering that it would likely end up on a high-end digital tier that even fewer people pay for, let alone know which 3-digit channel number is which. But CNN almost always having CNNI play second- or third-fiddle is endemic of a lot of U.S. media. U.S. news outlets are far less interested in world news and include far less international perspectives in their news coverage than those in other countries with a (mostly) free press. It's a shame, and it's frustrating for a lot of people like us who are interested in what's happening outside our borders, though at least we now have better options than we used to. AJAM and BBC World have made huge inroads in the last two years in getting into U.S. households, and there's so much available online now that it makes CNNI's absence on my cable box seem less relevant than it used to.