Do they really care about the essay, or do they really only care about your test scores and stuff?
My guess is that they would care if your stats are border-line or if you are going for the extremely selective invitation only merit.
It helps to write a personal statement as you then think about what you want out of an education and whether Mines is a fit for you. Mines has a high drop out rate as they really do not have a full business program or offer accounting mathematics so much, its a specialized school for geology, geochemistry, geophysics, applied math, petroleum engineering but you can study computer science and electrical engineering there too. Writing a personal statement is always in your best interests, as it forces you to look at yourself and the fit to the college in question.
This sounds like one of those optional statement that is really a good idea to complete.
Our son did the personal statement to show that he put in some extra effort for them and hopefully it will showcase his writing better than the ACT did (yikes, that was a bad score on the essay). He wasn’t sure if it would also help with the honors program invite or not.