Obviously there many factors that go into great lyrics. And I realize that some of it is very subjective. Also there has been many helpful tips and exercises to help create effective lyrics. Is it more than cohesion and rhymes? Does it have to have a profound meaning or can it be frivolous and yet still be enjoyed as a great lyric?

Honestly there are some who stick to a "rule of thumb" approach they have learned or developed. One common critique I have seen and heard is those who believe that lyrics can be too veiled or cryptic. "If I don't get the message than the words are not good". They say that although the writer knows the message the lyrics need to be explicit, concise and/or specific or the words are not efficacious.
Why there may or may not be merit to that I have a few questions. Doesn't the age of video kind of take care of that obstacle? Why not all videos are made to explain the song, there certainly is the option of doing just that. I mean often songs from a soundtrack mean more if you saw the movie.
In fact I tend to like songs that stop short of spelling it out. With the exception of it being an experience or story of course. What I am saying is why does it matter either way? Isn't the expression coming from the writer and not the hearer? Whether we understand the intended meaning or not doesn't mean we can't love a song does it? Maybe there really wasn't a significant point to begin with. Not all art is neatly wrapped in it's presentation.
Then again although I consider myself a very good lyricist and have written songs both specific and somewhat ambiguous, I relate to the music before I listen closely to the words. Even my own songs if the music isn't happening I don't care how awesome the lyrics are.
So what do you think? Do you have to have unequivocal definitive lyrics to consider the lyrics great or do you believe a philosophical style lyric can be just as effective and enjoyable?
For example is "Lucy In The Sky With Diamonds" have bad lyrics cause it really has no inherent meaning? Or do you consider say "Before He Cheats" a better lyric because it has a specific point?
Personally I find them both great lyrics.