There is a reason for that and it's because the mods take a hard line on editorializing the title of the submission. It's likely done automatically by a bot though.
The modification wasn't intended to make the title stand out, and it wasn't editorializing, it was deliberately adding information to help you, the reader, know what it was you were clicking through to.
I understand the reasons, but I feel that sometimes the mods revert titles without thinking, and without assessing why it might have been changed. Again, I understand the reasons, and having yet another time sink is perhaps unwelcome, but I'd like to see some way - like the "vouch" mechanism - where altered titles can be accepted.