It's cool. I don't understand that fear from it. Admin of a website has full access to site, files anyway. This is just extra feature what can help in some scenarios. It's helpful to be able edit nicely WP files without needs of ftp client, text editor or any other external tool. Sometimes admin need just small change - a color, analytics code, change footer. It's not more dangerous than editing a file via ftp, but gives the possibility to do some changes very fast in a browser.