Hypocrisy seems to be the word you are searching for and this is indeed my position and due to the Prime Directive and the toleration of Vulcan arranged marriage also the position of the institution whose name appears in your picture thingy.
you know, that's an interesting point. Sisko in DS9 says that a return to a caste system would be a deal-breaker for Bajor joining the UFP. Yet Vulcan's arranged marriages from before puberty thing doesn't seem to be one.
I guess being a founding member has its perks.
Personally, I think that the cultural practices of each world should be their own affairs up to the point of serious violence or harm.(Things like ritual murder or slavery would obviously disqualify, but arranged marriages and traditionalist caste systems would not, even if they were unofficially frowned upon.)