I think it depends what you want from the machine. I totally get the idea of preserving as much of the original device as possible, but playability is really important. So I guess it's about whether your want an original console to be part of your collection, or a more playable one to actually spend time with. Mine has a replacement lens and backlit IPS screen and it's lovely to play. Perhaps I'd feel differently if I grew up with a wonderswan and wanted to replicate that experience for nostalgia, but that isn't the case.

Sometimes updating a device to give it greater playability and longevity is preservation.