In an exclusive interview with Hideo Kojima, creator of the Metal Gear series, he complained that the size of the 50GB Blu-Ray discs were not enough for Metal Gear Solid 4. The producers of the title considered the disc to small and they had to compress some parts of the game in order to keep it on one disc.
Kojima : I am not satisfied with the quality yet, however... there isn't enough space.At least we know it will never be considered for another console release.
Interviewer: Not enough space.. on.. Blu-ray?
Kojima: Yes. (laughs) Not enough space.
[MGS4: Kojima says "50GB BD Not Enough For MGS4"]