Like others, I thought the "hi" feature (keyboard shortcut 5) was too easy and would trivialize saying 'hi' in the game. However, after a couple of weeks I now feel the opposite. Most people you run across in Ur hit the 5 key rather than just running past.
So, kudos; I think this actually was a good idea to make people who don't know each other (yet) more sociable. Hitting 5 is so quick and easy that it's not a hardship and yet the effort is noticed (or perhaps the fact of being noticed is noticed).