This is a fair approach. I guess I would just have a hard time putting out a list of the greatest reggae songs and including the Stones "Hey Negrita" or a list of the greatest heavy metal songs and including the Beatles "Helter Skelter" which is why personally I would limit it to artists known to be part of the genre.
But you are right a Ray Charles country song isn't any less of a country song than a Hank Williams Jr. song.
This is essentially what I was saying earlier. There are any number of artists that will have some songs that fit and some that don't.
As examples . . .
Kim Wilde: Kids In America (new wave), You Keep Me Hanging On (not new wave)
B-52's: Private Idaho (new wave), Love Shack (not new wave)
Police: Can't Stand Losing You (new wave), Every Breath You Take (not new wave)
Talking Heads: Once In A Lifetime (new wave), Road To Nowhere (not new wave)
INXS: The One Thing (new wave), Need You Tonight (not new wave)
Elvis Costello: Watching The Detectives (new wave), Veronica (not new wave)
Tears For Fears: Change (new wave), Shout (not new wave)
Berlin: The Metro (new wave), Take My Breath Away (not new wave)
Thomson Twins: Lies (new wave), Lay Your Hands On Me (not new wave)
Another group that some people categorize as new wave is The Pretenders . . . yet I don't really think they have many new wave songs at all (and I love The Pretenders). We just have to be open minded and have a broad birth, I guess.