/1/ Regional intimidation. In this era of unilateral action by superpowers (as the Chinese see it) they want to be able to bully and intimidate smaller regional nations. They can use it as a potential "stick" behind their diplomacy, especially when the USA is seen as over extended and unable and unwilling to come to anyone's rescue. The PLAN is therefore worthwhile even without firing a single shell at bending other nations to the Chinese will.
/2/ The potential to mount a short sharp regional operation, if the USA is otherwise too busy to react with its main force. The PLAN would have to wait for the USN to be busy elsewhere, before, say, supporting an invasion of Taiwan.
Meanwhile we've got 50 attack submarines so quiet the Russians can't hear them. 100 surface combatants equal to or better than the best they have, some with 4 times the firepower each. If every SAM in their navy hit an incoming US missile, they'd stop less than 5% of one salvo. Then we have with 1000 naval aircraft on a dozen supercarriers. Several thousand land based tactical aircraft. A hundred assorted conventional bombers with (alone) more missle firepower than their entire armed forces. Not to mention a dozen Tridents each of which can turn the entire country into a smoking irradiated ruin in less than half an hour.
The Chinese have the intention to build a real navy, one that can challenge us in the Taiwan strait. But they are just begining to enter the naval power sphere. Their navy is weaker than Indias. So is their air force. Japan's is better by a large factor. And none of those is even in our weight class. Only Russia's is, and only on paper because it is not really operational.
At one point in the article, speaking of carriers, it says the Chinese have "traditionally" relied on land based aircraft for strike against naval targets. This is a euphemism for not having any carriers. The reality is the Chinese air force has never conducted a land based strike against a major naval surface combatant. They've never hit any target that wasn't absolutely stationary. They've never shown they could even find one, in actual combat.
They are beyond green. Comparison with 1930s Japan, which waged a successful war against China for years, involving large scale use of modern airpower, before messing with us, is fanciful at best.
Are they trying to be a threat? Certainly. Is the sort of navy they are building one that Taiwan would have to worry about, 10-20 years from now, if the US didn't come help them? Yes. Is the sort of navy they are building, even as it will be in 20 years, the sort that could beat the USN, or even last 3 months against us? Not remotely.