Mystery Gift is still one of my most missed things about Pokemon. I wish more games implemented that kind of physical-digital reward system. Physically meeting up with people, always getting a prize, displaying your digital reward. Few games have a social system as intuitive and easy to use as Mystery Gift. The recent Pokemon generations have only made casual player interaction tiresome prerequisites for maintaining extra in-game content (I’m looking at you, Black City/White Forest), which is undesirable/boring, inaccessible for some, and frankly, nullified by wireless trading.
I think there is a place in today’s gaming world for more Mystery Gift systems (with a poorer-odds long range wifi version.) Reward people for going outside and interacting with people in real life, and give people who would prefer isolation a chance too. Like how you could Mystery Gift with Pokemon Stadium 2.
The Pikachu pedometers were an awesome addon to an already great system, despite it having slightly lackluster prizes (no room decorations). The Pokewalker was fantastic too, but it felt like an uphill battle with the reward system. Also I didn’t have any other friends who owned a Pokewalker so my favorite Mystery Gift aspect was sadly lost to me. :C
Maybe I’m just nostalgic about Gold/Silver, but they really did a lot of things right.
EDIT: Having recently purchased a 3DS, I just want to say how pleased I am with the Streetpass system. YES, NINTENDO, THIS IS WHAT I WANT.