BC was always a thing with Xbox, the handfull xbox games that you could buy digitally were available to play on your 360 with your account and the bc 360 program was in the works while the 360 was doing great. The Wii was praised for its VC so criticising the Switch for not having it is fair. I really don't understand how people can call 'the ability to play games you bought before on your new console' a weakness. It should be mandatory by now.
360 was not doing great by then, ps3 was catching up real fast even tough they released the ps3 1 year after the 360. Backwards compatibility was also very slow, just a few games every few months.
The wii was also not doing great by the time of VC, the wii sold a lot to casuals in the first couple years. But the wii was never praised at all for the VC, maybe if you read the gaming news yeah, but most people who had a wii were casuals who didn't even know about it.
But that's besides my point anyway. My point is, Nintendo doesn't need to bother, money will be coming in with little to no effort. There's more money to be made with remasters than VC.