I know that I personally I have at times struggled with the Chinese language and I understand why a western observer might be inclined to disparage Chinese as somehow insufficient, but I think it's pretty clear that most such complaints would be a product of linguistic and cultural upbringing and not with the Chinese language itself.

Let's just briefly consider how you would evaluate the claim that a country/culture was "held back", whether by language or something else. World cultures being as diverse as they are, what metrics would you use to judge whether a country had been "held back" or had gotten ahead? By the existence of stable and authoritative governments? By its cultural products? By technological achievement? On each of these metrics until very recently (historically speaking) China has been on par with if not ahead of any other contemporaneous nation/culture. I disagree with a lot of Chinese historiography, but it's pretty much undeniable that for 2,000 years, a succession of Chinese dynasties maintained highly qualified, highly educated beaurocracies managing large empires. Up until the industrial revolution Chinese manufacturer was in a lot of ways far more advanced than that in the west. China has a long history of high level philosophy. It should be said, some scholars suggest that up until relatively recently (150-200 years) literacy rates were higher in China than basically anywhere else in the world, hardly what you'd expect from a language that is too difficult to learn or stunted people's growth. China mass produced books by woodblock print hundreds of years before Gutenburg.

On some levels, Chinese written language could actually be seen as a major aid to Chinese civilization. Chinese oral languages are very diverse. The Chinese call them "dialects", but many are clearly distinct, mutually unintelligible languages. Written Classical Chinese acted as a written Lingua Franca, allowing people to communicate across large distances and even cultural divides and facilitating the ruling of an empire which was both in terms of landmass and in populations clearly among the largest, if not the largest, in history.

Counter example: Japanese writing uses Chinese characters extensively but Japan was still able to adopt Western technology and science and industrialize extremely quickly.

Chinese characters are actually fairly easy to create or to adapt for the phonetic representation of foreign words. There are much better explanations of China's reluctance to adopt foreign innovations than their writing system, namely, their entire canonical Confucian text focused bureaucratic exam tradition.