It's needed and it's pretty simple to implement.
Quick and not perfect (I'm weak perl programmer) is to change in newreply.pl (because HTML is enabled in this board I used [ instead of < and ] insted of >):

[textarea cols=$TextCols rows=$TextRows wrap=soft name="Body"][/textarea]

to:
[textarea cols=$TextCols rows=$TextRows wrap=soft name="Body"]> $Body\n\n[/textarea]

To replace [br] with newlines before `print qq~' add line:
$Body =~s /\[br\]/\n> /g;

Deleting lines beginning with `>' should also be considered to prevent too much quoting.

Greetings,
Piotr