I think part of the answer lies in what type of learner you have. DD and ds both love to read, but dd doesn't do well remembering how to spell words. I do, however, think that part of this is due to the fact that when she was very little I didn't have her fix her mistakes out of fear that she would no longer enjoy writing.
The problem is that she wrote some words so many times the WRONG way that it was ingrained in her mind that way. She learns better from the repetition of writing and learning spelling rules.