Sure, it's easy to grab a first name from a database or glean some info from a profile.
But when you pretend to know me, you've already started our relationship with a lie. You've cheapened the tools we use to recognize each other and you've tricked me, at least a little.
Direct mail used to take advantage of this technique a lot, and since they measure everything, they knew when it worked. Online, though, we're seeing less disciplined marketers (big and small) continually mess it up. The clues are obvious to even the untrained eye–typefaces that don't match, references that don't make sense, and most of all, the weird disconnect we get when we think we're supposed to know someone and can't remember who they are. That's a lousy mood to get your prospect in, I think.