>Would you say that Japanese 'sensei' is patently wrong for 'you'?
>What's the problem of using (idiomatic) nouns for pronouns?

>**Henrik

Actually sensei isn't used for you. Sensei is used for people who are
teachers/doctors and such, it isn't the same as you, as you refers to the
person, irrelevant whether it's the speaker/hearer or attribute/property of
the person. 
The Japanese use a lot of words for 'you', kimi, anata, anta, omae, etc. But
usually they aren't that direct, so they use the surname with -san or a
different 'affix' (including sensei) or 'a nickname'(person who does) or
actually no pronouns at all.

Speaker and hearer, the one who is speaking/hearing is different everytime
on top of that, what if a sentence features the 'displacement'? What if the
speaker isn't speaking at all. 
So I'd go with that hearer/speaker isn't a good term for you and I. 


You can use idiomatic nouns for pronouns, but when which exact meaning is
used should be arbitrarly explained and used.