I wonder what segments will be promoted on the packaging on volume 2, if it comes out. The packaging for volume 1 pretty much only mentioned songs that are included, without talking about specific non-music sketches, I guess either becasue they didn't want to list an official title (not many people would know the official titles for each segment), or they didn't want to describe any particular moments. Of course, segments could have been described. The songs aren't the only material from the show that are really famous.
Here is how the box could have mentioned some non-music segments: "Relive such famous moments as Ernie making a clay sculpt of Bert, the story of The Monsters Three Wishes, the Sesame Street News report on Rupunzel, "A loaf of bread, a quart of milk, and a stick of butter", and The Amazing Mumford turning Grover into a rabbit, among other moments".
Most of the songs from the first five years that most casual fans are most likely to know about are included. While a lot of these songs were remade, and some were even remade during the first five years, people might not be aware of the fact that songs were remade. They may be familiar with certain songs but not neccessarily any specific version (though I think Rubber Duckie and C is for Cookie are exceptions). I am a bit surprised that all A-list songs weren't mentioend on the box. Still, suppose the next volume has different versions of The People in Your Neighborhood, I Love Trash, Bein' Green, and other songs that were remade and included on the first set. Casual fans who bought the first set who don't understand that they were remade might see them mentioend on the packaging and think that it's just repeating certain skits.
There are some songs that I associate as A-list, or very high B-list, that were not included in any form. Songs like Sing, Count it Higher, The Ballad of Casey McPhee, Somebody Come and Play, Mahna Mahna (though Sesame Workshop would need to secure the music rights to release it), and possibly Everyone Likes Ice Cream, Five People in My Family, and Everybody Eats. Of course, that's depending on if the next set focuses on the first five years again or if it focuses on the next five years (there is still a lot of classic material from the first five seasosn that are not on this set, but then again, material from the first five years would also be repeated in the episodes included on a 1974-1979 set).