I use this when the tone of my email would otherwise be, where's my spreadsheet motherfucker?? It's nice to modify the overall tone of the email to something more friendly. I have a very curt writing style so I'm often concerned my emails will come off as blunt or demanding if I don't include a pleasantry.
I work in a very friendly, informal field so I find myself doing little pleasantries to fit in, email-wise.