Because they don't need to? If a game that pushes the hardware to the limit like SMG2 can fit in a single layer DVD, why they should? NSMBW fits in about 300mb, even if the game was 10times longer it would still fit on a DVD. If they need more space on disc they use a dual layer like they did with SSB and now with Other M, I don't really get the problem, ...also the detail that you put into the game depends on the hardware capabilities not by the size of discs-.-







