It means that writers who are not willing to dedicate effort to their work will not produce enjoyable reading (novels, poems, etc). I can immediately see his point when I think of Crime and Punishment, or T.S. Elliot's poems... Are you a writer, by the way? You have to keep in mind that Johnson was a lexicographer - he worked with words, not only as a writer and poet (a lexicographer is someone who writes, or compiles, dictionaries). It is worthy of note that he was a demanding perfectionist, which would account for the quote you mentioned, William Lee. This may have had to do with his posthumously-diagnosed Tourette's Syndrome. On the other hand, he once said something to the effect that "a man must write about things he likes, otherwise he will not do it well", which could be construed as a contradiction to the first statement. Personally, I might have liked to read Samuel Johnson were it not for his sexist remarks; this made me lose interest in finding and reading his material.

It means that if a poem or story is badly written and shows a lack of intelligence, readers won't like or appreciate it.

thats u write without ur feel without ur mind u write it nimbly without sensation