I kinda think Nintendo's older back catalogue has never had less value as it does right now and that's part of the reason why this is underwhelming.
Why?
1. The Switch has an insane library. More quality games at reasonable prices than anyone could ever play. In the past, this wasn't the case and returning to previous favorites made a lot of sense for a couple bucks. But now for 5-10 dollars you can get all kinds of incredible indie games on the e-shop.
2. We've all played these games on modern hardware. For those with a nostalgic connection to these games, getting to play them on the Wii was magical. A glorious and unexpected return to childhood. But since then, they've been on the Wii. They've been on Wii U. They've been on 3ds. Most of the Nintendo audience that would be interested in these games has already played them again, and the novelty of having access to them is lost. They don't even really move the needle on hardcore forums any more like they did back in 2006-2008, where SNES Roms would get replay OTs.
3. N64 games, being early 3d games, just don't age as well as SNES games. There's only a handful worth playing, and most of us have played them half to death already. Not a huge value add.
4. Nostalgia tends to work in 15-20 year periods. When you're 25 you're nostalgic for stuff that came out when you were 5 to 10 years old. When SNES games launched on the Wii, that was exactly 15 years after the SNES. Well, 15-20 years ago was Gamecube and GBA territory, but Nintendo will absolutely not be adding GC to the service, and currently isn't adding GBA. So we're stuck outside of the prime nostalgia zone.
It's just not the killer feature it used to be, imo.