in my opinion there is no way that you can write good essays just by reading someone else's essay. At the University of British Columbia students are require to think and bring up new topics or new ideas for most essay or paper assignment. i think that if someone wants to improve there english essay skills, he or she should practice writing, proofreading or get someone to proofread and understand how the person edited your essay thinks or to try not to make the same mistakes over and over again.
so in my opinion if you don't write or just read essays, it won't help much.
most people improve by writing essays, getting proofread and rewriting the essay and understanding the problem or errors.
reading essays will only improve reading skills and vocab but not writing skill.