I think the perceived lack-of-value for them is related to how easy it is to write lyrics down, compared to any other aspect of the music. Anyone can do it within the time of the song, usually first try. Any other aspect of the song cant't just be written down from ear (yes, including the sheet music, which isn't nearly expressive enough to reproduce a performance*).

*There are some funny "play from sheet music without knowing the song" type videos out there, with funny results. YouTube/google search is no longe usable, so I can't find any.