If the goal of the PLA-navy is to limit itself to within the "first island chain" of mainland China then you are absolutely right. However I think it is safe to say the PLA-navy has far greater ambitions then that. China already has the first island chain pretty "secured". Within 5 years it will be the 2nd island chain. Within 10 years it will be the 3rd island chain.
Ultimately, I do think that the goal of the PLA in the near to medium-term future is to try to bring Taiwan beneath the PRC flag. One Taiwanese ports and land is open to PLA expansion, then the PLA would have far better access to the Pacific and far more reason to deploy fleets of hard-hitting anti-ship destroyers to the Pacific.
Prior to that, however, the focus of the PLA would probably still be on Taiwan and ensuring that Japanese and American forces can't stop China from securing the island militarily should such a possibility become a necessity. As the PLA's budget isn't infinite and, quite frankly, is still actually quite a small proportion of the GDP, I just don't think that a massive fleet of Type-055s are the best use of resources. The ballistic missile umbrella is excellent and probably needs more resources to continue developing, but there are areas where the PLA is REALLY lacking. The fleet of 5th generation aircraft like the J-20 and the FC-31, for example, are tiny in comparison to the kinds of unit volumes that America and Japan could field in a long war and the H-20 is still not operational as far as we know. Considering how vulnerable Chinese vessels still would be in the attack submarine-infested waters of the Pacific, the ability to secure air superiority way past Taiwan and to fly PLAAF ASW planes over the Pacific is kind of the very baseline of what is needed to ensure that the Type-055s can really operate as anything than a very expensive platform to mount a radar suite and missile systems.
It hurts me to say this because warships are literally my favorite weapon system. I still can't help but think that building out the Type 055 fleet way past what is needed to test out the hull form factor and develop competencies is just nor really what the PLA needs when their airforce is still comparatively so weak and when the continental PLARF are probably better suited for targetting American CSGs regardless. I think that 8 type-055s just aren't as good an investment as 100 J-20s/FC-31s.
