I've never actually used CIWS, under the assumption that there's no place for them in real combat since they only protect the ship they're mounted on. Are you saying something about the recent change made them more useful (you allude to being able to target multiple missiles in a salvo, but I thought that was already true for other weapons)?
I'm regularly seeing large salvos of missiles spaced 5 or more minutes apart. Given that spacing, the fast fire rate of railguns, gauss, and lasers is pretty much wasted (yes, I understand that this will not always be the case, some other enemy may prioritize full firing rate salvos in close spacing). Given that, lasers are the only one beam PD weapon that offers a reduced size in exchange for reduced firing rate, which in that scenario is getting reduced size for free meaning you can mount more! Plus since they're smaller, the lasers are cheaper and require less crew.