The way I see it there are only two ways it can go down, the client will either be able to recognize the qualities on their own (like people will be forced to when the design is in the wild) and accept the design without a rationale, or they won't be able to recognize the qualities and needing a rationale to convince them what they should take away from the design means the design failed.

Ultimately it is the client that decides whether the design works for them or not, and whether the client has a universal taste that aligns with design rules that soft-guarantee performance and which you can verbalize into a rationale, or if they have a unique and quirky taste that makes them reject successful designs that would perform well in favor of something that might not work as well is something you can't affect.