Going back a few years, a fair number of kits had a proprietary name as part of their name, e.g. "Port". Given that kits are more popular now and evidence on this forum is that Canadian kit vendors sell in Europe, the reason for adding "style" is probably trademark / copyright protection. While the kits are juice/concentrate and exempt from wine laws, the names are protected -- I recall reading an article about wine name protection being enforced across the EU. While the kit vendors might be able to prevail in the courts, it's a an unnecessary battle that will cost even if they win. My mom used to comment about people, "cutting off their nose to spite their face."
FWK isn't doing this, but they also sell only in the USA.
A secondary thought is that consumers are more wine savvy and may question a Bordeaux kit made from California grapes, but if this is a reason, it's a distant second.