And while they will never attain the status of the others, it's not for a lack of abilities or songs. In fact, some of Robison's songs have been hits - albeit, not for him.
Willis and Robison just released "Beautiful Lie" in June, which is far more than the lovely cover of them singing, while facing each other with drawings of stars and hearts in the background.
They dove into about half of that live - more would have been even more satisfying - while also playing songs from previous joint recordings and, of course, their own solo material.
At 50, Willis' expressive singing has retained its luster, especially on songs like the slowed-down, pretty sounding "If I Had a Rose" from the new disc with Robison pitching in on backing harmonies.
Robison doesn't have the vocal chops of his wife, but he did well with more upbeat songs, such as "Border Radio" and "Rock and Roll Honky Tonk Ramblin' Man" along with the request of the humorous "What Would Willie Do." He also looked back on his days of growing up in Houston on "Astrodome," a new song penned with Jack Ingram.
Robison reached back into his songwriter's catalogue to trot out "Travelin' Soldier," which reached number one for The Dixie Chicks the same week that lead singer Natalie Maines made her infamous statement criticizing then President George W. Bush while in London, promptly sinking the song Robison may have offered light-hearted comments both before and after singing it, but this remains one powerful song about young love for a soldier that ends up with him coming home in a pine box.
Robison also turned in worthy versions of "Angry All the Time," a 2001 hit for McGraw and Hill and "Wrapped and "Desperately," both George Strait hits, even though the interpreters do may have better voices than Robison.
As usual, Robison and Willis had a supple backing trio, led by their longstanding guitarist and pedal steel ace Geoff Queen. Low key though he was, his musical depth was not.
To say that Willis and Robison deserve a lot of credit in keeping alive the longstanding country tradition of musical couples (George and Tammy; Conway and Loretta; Johnny and June to name only three) would be an understatement. That in and of itself would be a worthy endeavor.
It is our good fortune that they have maintained their musical integrity.