From this profile:
It’s easy to write songs like Jim Morrison. No disrespect intended to a charismatic frontman and a great rock band, but everybody can and has written blatant attempts at poetry, shrouded in so much imagery that only the most astute listener will know or care what the songs actually mean.
It’s tougher to write something that is intelligent, yet so simple that you get it on the first listen, get the melody stuck in your head for days at a time and discover a new layer of meaning on every listen.
Roger Miller is Hank Williams’ only rival in this regard.
Even more difficult is writing songs with humor, but not coming off as cheesy. Very few people do this well, but Roger Miller was the master.