The problem probably wasn’t that they didn’t know how important netcode was, but rather they were not capable of doing it. XIII’s console netcode was confirmed to be outsourced to another company who probably didn’t give a shit about the rest of the world. When Steam Edition came out they hired people who could handle it. You can talk to these people on the Steam forums and they’re dudes from Australia, so SNK’s Japan team still probably isn’t capable of making their own netcode, but they are taking steps to fix it. XIII’s netcode is more than playable and Metal Slug 3 is rollback netcode. They understand the problem.
As for this release, SNK likely has nothing to do with it. Tencent probably licensed it, and Tencent does not give a jack russel terrier about any country that isn’t China. They even use rollback netcode because they know a lot about networking, but they tie it to their servers in China so that it’s worthless to anyone not close to those servers.