For me, most lyrics go over my head, i hear them simply as any other instrument... probably from my proficiancy (cannot spell that word.) in cantabile.
It solely depends on repetition of either voice.
If they feel like the piece could go with out... (in which i find a lot of rock to be pointless in this manner. (Like Rush, later AFI, or 90% of those Pop-punk bands.)
There are some i prefer they never had a singer like Dream Theater and that specific progressive rock.
Grunge Rock should never have existed. -_- that is one genre no one can convince me to appretiate, everything in it can be found in other locations with more dissonance or even more profoundity.
Metal and all it's subgenres are a hit or miss... some are really good for lyrical counterpoint some are just WHAT THE HELL?
Kiss... is another perfect example of no lyrics needed.
Onto pop. Pop is way too overrated. It relies on background lyrics. Droning out to some madness and causing such invigerating beats just with different colours attached to their songs... though pop has changed since the Beatles.
However with the lyrics being the prime focus it would enhance it... there are few pop artists who i would say it enhances, as they still incorporate a story or even a concept, rather than having a meaningless monotonous value...
Gospel and Contemporary Christian Music each have their value with lyrics, but again... please go back to hymnals and study those first... It just sounds like you are really trying to swoon Jesus so he invites you into his bed... (seriously... compare with the boy bands of the nineties and the Free Jazz bands of the Roaring Twenties. then tell me...)
Now one of the most well know works of all time is Beethoven's Ninth Symphony. It was innovative at the time because no symphony had used choir prior to this. At the time he was fully deaf and not realized that the music was complete and behind him was a standing ovation.
Personally i find that lyrics get in the way of the music especially when i am trying to concentrate on something let alone a discussion.
I may beable to hear a hundred different nuances of instruments being played at one time, but when someone is talking... it takes my focus away from their talking because the music is trying to tell me something...
I am a pianist composer... i tend to not sing very often... i tell a story with music using techniques of cantabile, dissonance, harmony, atonalism, chromaticism, ambient aleatory, and most of all emotion.
However... this specific recording of Fauré's Requiem is truly awe inspiring...