What is the purpose of the 'mi' here?
I was wondering the same. I wrote "What good writers we are."... not good :P
It's funny because it could be understood your way, but that would be an archaic, today not used form of the Hungarian sentence (now it is "Milyen jó írók vagyunk"). Actually here the "mi" simply means we, and it is not necessary.
"Mi" also means "we"
When learning Hungarian they often add the pronoun even when its not needed. Maybe to help us in our learning and to be understood. It can be added in for emphasis but it isn't for this sentence.
Does anyone else think that this sound is odd, or is it just my hearing?
A little bit odd, yes, but still acceptable.
Isn't the use of "van" only for "how" and "why" questions? Unless it's used for saying how good the writers are in this case?
(Én) jó író vagyok.
(Te) jó író vagy.
(Ő) jó író.
(Mi) jó írók vagyunk.
(Ti) jó írók vagytok.
(Ők) jó írók.
This is a type of sentence where van is dropped. But that dropping only happens in third person (singular or plural).