Music is another language, It is just a tonal one with 12 different sounds. i start praying with a guitar in my hand and at some point I stop speaking and start singing. It is interesting sometimes I can't remember the song sometimes I wouldn't want to share the song and sometimes I get it down on paper.
I don't think it is important to write it I think that it is importaint to sing it if you are gifted this way Psalm 96 says it all.
however if you are writing songs in this way you will be singing songs to God this is good. If you want to write a song to your bro/sisters you need something worth saying. Bible and life are the places these come from.