To-be-honest, many layman in the public usually don't understand the importance of Central Asia, mainly because they are mostly known in history textbook as former Soviet states that got their independence after the disintegration of the USSR.
Other than energy (uranium ore and oil & gas) and food (grain), there is one other yet important thing that I believe is crucial for China - defense.
For one thing, as long as Central Asia is securely under the influence of China and a pro-China Russia, China has little to worry about her western frontier. However, since the attempted colour revolution in Kazakhstan early last year plus the worsening Russian influence in Central Asia due to the war in Ukraine and Moscow's recent beef with Astana, China must be prepared to step in and fill the void left by Russia in Central Asia in order to secure and defend her western rear from any attempts of coercion and subjugation by the US-led NATO.
Apart from preventing NATO from having any significant military and political presence in Central Asia (military bases, observation (read: spying) stations, training grounds for Muslim extremists WRT Xinjiang and the BRI, etc), Central Asia is also very useful as per below:
View attachment 107576
US strategic bombers based in Western Europe can reach western China to conduct strategic bombing against Chinese military and civilian infrastructures and industries from that direction.
For the defense of China further out to the west:
1. Turkey is a NATO member and is harboring Xinjiang extremists and seperatists, hence they are unreliable;
2. Azerbaijan is allied to Turkey and has close relations with NATO, so they aren't really dependable either;
3. Georgia is pretty much a de-facto NATO member since 2008; and
4. Armenia, despite being a Russian ally, can be easily bypassed.
Going up north to Russia is certainly a no-go, and the same goes for Iran down south. Hence, the only way that US bombers could ever reach China's western frontier would be through Central Asia.Therefore, Central Asia should play its role as a geopolitical and military barrier in order to prevent NATO from conducting long-range attacks into China's interior from the west.
This would very much require China to significantly beef up her involvement and influencing efforts in the region in the coming years.