Hello,
When we use "INSERT ... SELECT" statement even if one row is not acceptable for the table whole statement is rolling back and almost there is no information about the row that cause to error. this error could be, unique constraint violation, too large value, not null constraint etc. I know that there is a dml error logging mechanism but it is not easily implement all the time, especially if insert statement is coming from application and application has no any structure to define it.
it is also something that developers deal with all the time and it would be much more easier if while Oracle was generating this error, could give the information about that row. of course in a "perfect" system shouldn't have this kind of errors but there so many systems that design in many years ago by people who is not expert on DBs and we have to work based on these systems. so I believe it would make our life much more easier.
thanks.