Compared to say, the SNES, Mega Drive, Nintendo 64, etc?
I mean, quite a few SNES games have been hacked or translated (Super Mario World's scene is particularly impressive here), and there's some work going towards N64 hacks too (mostly Mario 64, Banjo-Kazooie and the Legend of Zelda Ocarina of Time), but the focus for a lot of the ROM hacking scene always seems to be more focused on NES titles. And homebrew? Well, that's pretty much all NES and earlier, the number of SNES homebrew games is about 30 titles at the most.
So why is the case? Why are there so many more hacks of NES games than anything later? Why does the homebrew scene seem to cut off around the NES era? Why is so much of the coverage of the ROM hacking world off site focused around NES games more than those for other systems?