Granted, the girls have become quite silly as opposed to when they first started. For instance, you have Minimoni singing about drinking milk and eating green vegetables while the Musume themselves are dropping and chopping on Renai Revolution 21. But this is to be expected from an idol group. As idols they are watched by the public and must entertain. This does not take away from the meaning of their songs, however.
Idol groups can have meaningful songs.
Moreover, the antics on-stage only go to enhance the enjoyment of the song. Their appearances on Utaban show the viewer that these girls are more than idols and that they have a sense of humor and some semblance of personality. With that being said, I appreciate Morning Musume as a group and I enjoy their songs. True, I too sometimes hope that the next single from the girls will be the next Furusato. However, if that is simply not the case, if I can find enjoyment in the single itself, I am content.