TH3_ST0CK on 04 November 2016
If I had to guess, I would say the extra power is to ensure accurate emulation. While many emulators of the NES and SNES today don't take up too many resources, they aren't really as accurate as they could be, especially with regards to timing, as described in this article: http://arstechnica.com/gaming/2011/08/accuracy-takes-power-one-mans-3ghz-quest-to-build-a-perfect-snes-emulator/
Also, I would imagine with a more powerful GPU, it would be able to overcome any visual differences that crop up on a more simple emulator. You can see the difference in image quality between the NES mini and the Virtual Console below.
