DVD drives that can read Wii discs are
super rare, but here's an interesting one—BluRay drives that can PS3 discs are quite common!
Unfortunately, ripping them still isn't an easy process. Last time I did this I needed three different programs: A generic ISO creator followed by "PS3 ISO Patcher" and then finally "3k3y ISO Tools".
This is an area where I'm actually a bit disappointed in emulator developers—RPCS3 ought to automate this process. I realize they're working for free in their spare time, but... if you're going to say that your software is intended to be used legally, I think you have some responsibility to make that the legal path accessible.
> I think I would probably buy the game and then download from an internet source, if I wanted to emulate but stay honest.
Sure, and I've done this to, but there's basically zero chance of anyone doing that at a larger scale. What we want is for the level of friction required to acquire and play a legitimate copy of a game in an emulator to be at least somewhat comparable to the effort required to find and download a pirated copy.
People who play on real hardware are much more likely than emulator users to track down actual games. I suspect that's because—even though piracy is readily available and quite easy on these consoles—using a real disc can feel a lot more straight forward.