Answer to this question is pretty straight forward, have you ever sent any Email campaign without tracking opens and click-throughs? Then why only track Emails and not attachments?
In this modern world, if you don’t make most out of technology, you will be lagging behind your competitors. Keep in mind that your clients are already tech-savvy. Everybody knows life in the tech world moves quite fast, and if you want to survive, you have to keep up with the pace and adapt to new technologies.