I think it's the same reason that excessive bold or ALL CAPS are not enjoyed by most: it's a distraction. Instead of focusing on the content of what is being written. I think icons, just like bold or CAPS, can be used in situations where it adds value (formatting pun intended) - but often times it's poorly used and distracting.
I have no idea what you've typed there. All I see is a heart and three boxes. And it doesn't seem that the boxes are decodable either. Whatever it originally was has probably been irreversibly replaced.