By now, we all know about the collection of Mega Man Classic titles released in North America several years ago under the title Mega Man Anniversary Collection. Japan never got this game, but they did, however, get the first six NES Rockman games re-released on the original PlayStation console. What's more, they had the opportunity to purchase each one separately at a regular retail price-- no value-priced compilation here. But these six titles did go on to form the base of Mega Man Anniversary Collection... but not in their entirety.
While we did get the Navi modes, featuring Beat and Mega Man's friends guiding us along, some remixed music, and the turbofire feature, there was so much more which we didn't get, including art and enemy encyclopedias. Not to mention the Pocketstation feature, which provided additional mini-games and a way to give your life meter a serious boost-- of course, shy of working with Nintendo's GameCube-Game Boy Advance connectivity, I don't know how they would have done that anyway.
See the series' promotional clip from Japan for yourself:
I still think the greatest loss was the enemy data... that would have been nice to use for The Mega Man Universe wiki earlier on.
News Credit: Protodude's Rockman Corner