Continuing what DragonDePlatino said, the other reason why tracing isn't welcomed is due to how simple/easy it is to pull off. If tracing is that impressive of a skill, then this world will be flooded with "artistic geniuses." We'd be more impressed if you actually took the time to create all these assets yourself and quite possibly put your own spin on them.
So what if your sprites are not perfect if you work without tracing? We all have to start somewhere and even the best of us were rubbish starting out.
So what if your sprites are not perfect if you work without tracing? We all have to start somewhere and even the best of us were rubbish starting out.