Well, we did get the Japanese 'Treasures' album, which was just as described. But, like you mentioned, everybody would have their own ideas on which tracks to include and not include....creating very different playlists. : )There was over the years a small set of outstanding songs that were long and still made it big on Top 40 radio - how the hell long was "Hotel California" or "Stairway to Heaven" - and this could have been another one. Adult Contemporary radio would have played it I'm sure, and they had a lot more big hits there than on Top 40. It was such a superior arrangement and performance that it deserved to live on the airwaves. I agree with Ed about the superb instrumental sections (often wishing the flute part was even longer) and that they should never be cut. These same things can be said about their remarkable cover of "A Song For You".
Here's the thing: if every great song that they ever recorded that wasn't originally released as a single, but were released as a single now, one would have an extended album jam-packed with incredibly beautiful music...everybody would have their own list, but I bet a lot of the same songs would be mentioned repeatedly...what a great tribute to Karen such an album would be: "Carpenters: The Singles That Should Have Been".