I think apt use of does demonstrate sophistication, just like, it seems, in Chinese. are taught at the level, with other parts of the curriculum being , literature, etc., which alone should tell you something about the perceived status of these "idioms".
The infamous exam question is:
> Complete .
with the correct answer being , _not_ .
In serious writing, are analogous to the poignant use of idioms, which one finds in well-written newspapers, for example. Maybe less like "raining buckets" but more like "skate on thin ice"...