Does a perfect job? The Long March 2/3 are hypergolic (toxic fuel) rockets with launch sites deep inside China which regularly drop stages close to where people live. That is why they are building the launch site at Hainan and why they bothered to develop Long March 7/8. Building a new inland launch pad for those rockets is a step backwards.
Don't get what you want to say, but certainly you started thinking without a clue of what China's requirement is.
First off, who said China is building new inland launch pad for those old rockets?
Secondly, the inland launch pad will be there FOREVER. It is a strategic backup, regardless the site of dropped stages. They will try to minimize the size of dropping area, but never abandon the sites. You can read the requirement of "New high altitude launcher" (LM-8 and LM-7A), there is a specific requirement of capacity from Xichang and Jiuquan sites. Also the requirement of them being 3.35m max in diameter, that is for inland rail transportation.
Thirdly, mind you, LM-7 and 8 have to be able to be launched inland, that is what the state demands.
Fourth, hypergolic is quicker than cryogenic (LO2 included) to launch. It can be fueled and wait on the pad for longer time. Another must by military until the capacity can be replaced by solid rocket, don't know when that will happen yet.
The perfect job includes the capability of launching most of satellite in a time of war when the coastal sites are in danger. The world is not so rosy as you wish and China is certainly preparing for the worst case scenario.
I am aware that you are a fan of SpaceX etc. But we are talking about China. And not only technological demand but strategic and security demand. Think about SpaceX as a Ferrari, but LM-2/3 are the rough off-roads, orange and apple.
