I think there are two issues here, the first that China has a general bad image abroad.
I wan't to be careful with my words here since I can't read the mind of billions of people, but I do believe that most people who haven't been to China have a really inaccurate picture of what what China really is.
Now I'm not saying that anyone who get more educated on China or even live there will immediately fall in love with this country, this is demonstrably false, but I do think that as a whole, if people knew and understood China better, it would have a generally more positive view in world. I don't know if it would make the overall opinion of the rest of the world to be OMG we love you China, but I'm fairly certain it would improve, and specifically, I think a lot of the fear (but not all of it of course) would go away.
The 2nd more specific question is why Chinese media is not popular. The short answer is that it's just not that good. I know I'm painting in a broad brush, and yeah it's subjective but honestly, it's mostly shit, let's move on to the important question which why is it mostly shit*.
Indeed, the CPC control and censorship is indeed part of the issue (though once again, I think people have a bit of a inaccurate mental image of how those things work in China, though I'm not sure that this is relevant to this point) but I don't think it can explain everything.
I mean you look at movies that were produced in USSR, a more restrictive regime than China's, and while it could never rival the output or influence of America, it did manage to produce some masterpieces of cinema. Yeah, not everything made in China is awful, but so far China hasn't produced your Andrei Rublev or Idi i smotri. Not even close.
And I think the reason for that gap is that China until pretty recently was mostly closed to the world (more than the USSR ever been) and really didn't have a middle class. We are living with the first generation who was born into the middle class in China. And building a film industry takes time, I honestly don't think this is something you can go from zero to Hollywood in a generation.
And then there is the language.
* I'm talking here about stuff that would be exportable to other part of the world, there is actually a ton of very interesting art being done in China on a smaller lever/for smaller audiences.