Well it wouldn't take much to have every Nintendo NES, SNES, N64, GC game they published run on their newer systems and to have a library like Steam for accessing them.
There are several games they published and had on the Wii I purchased that if were available in a library format on the Switch might make me think twice about getting one. Sony did it with the Vita/PSP, Microsoft is doing it with their hardware.
Its understandable Wii/Wii U games might not work, but practically every other console pre Wii can be played via emulation on the PC, so why not on the Switch, and why should we buy the same games over and over again.
If people buy digital music, which is a license like software, nobody tells them they can't play that music on their tablet, smart phone, IPod, Computer. Imagine if Steam was limited to one computer, and that's how Nintendo behaves...
Seriously, if I could just get my digital games on my Wii for the Switch, even just the Nintendo published games, without having to buy them again, it would make it a decent option. But Nintendo is Nintendo, and that doesn't seem to be happening.