I was published in Sports Illustrated and judging by my typo filled chats here, I’m a horrible writer.
That said, having a letter to the editor published doesn’t demonstrate good writing. It demonstrates that the NY Times saw fit that the content of what you had to say was relevant to that day.
And then there’s this - which also would impact your writing - * Letters may be edited and shortened for space.
Bottom line - having a letter to the editor publish is a personal source of pride for you but it adds zero value to a college application.
Good luck.