Bigger worlds, 16x more space (or greater) used for textures (high definition textures), alot more textures, alot more music, higher quality music....its easy to see how you could make a game that would require a BRD.
As for more advanced compression techniques, current-gen games already heavily use compression. Whilst the X360's processing power allows for more efficient techniques it isn't going to drastically reduce the size of files over current techniques. Xbox360 developers have stated that a DVD9 is not big enough for next-gen games, I see no reason to doubt them.
As for more advanced compression techniques, current-gen games already heavily use compression. Whilst the X360's processing power allows for more efficient techniques it isn't going to drastically reduce the size of files over current techniques. Xbox360 developers have stated that a DVD9 is not big enough for next-gen games, I see no reason to doubt them.