We're not talking about whether China is worth visiting. I think so, my tourist visa experience was in fact applying to walk a part of the Chinese Silk Road in 2019 with my (Cantonese-speaking but non-Chinese national) wife and we were politely told to shelve that particular idea permanently. There was no visa-free entry at all back then. We ended up going to Macao instead, and had a good time, though not at all what we originally planned.

In any case, the question was whether learning a Chinese language allows you to go on unique tourist experiences that would otherwise be unavailable. And the answer is that it doesn't, certainly not to the extent that it's worth learning a language, because, as you yourself state, you don't need to know the language to visit the approved destinations, and while there are some experiences that would require you to know the language, they are anyway outside the approved set of destinations and you'll be blocked using all bureaucratic systems from visiting them anyway.