Well, it doesn't add anything, but I wouldn't say Meta has a really bad case of 4MSS. Grabted it'd like more moves lots, but that goes for almost everything. Meta's movepool is actually not that great, so the fact that Pokemon only can have four moves is really a good thing for it, since it means opponent's are less likely to have their best moves for it(like EQ on Kang and Flare Blitz on Talon. Ofc those are still reasonably common, but not as much as if Pokemon could know six moves.)