Characteristics of good test case:
Effective(It will find a fault)
Exemplary(It does more than one thing)
Evolvable(As software changes the tests need to be changed)
Economic(Using minimum time and resources)
Are you assuming that if one person write test case he/she will also be writing bug report for the same? It may or may not be the case. IMO, good test case should facilitate the process of finding more defects efficiently in the product.