Let me ask this: you've got great music - instruments, melody - why would you NOT want good lyrics to go with it?
I can answer this one.
95% of people who listen to music (or whatever percentage it actually is) are simpletons who don't understand lyrics that are deeper than something like "I just met you, call me maybe" or "my anaconda don't" It's just the way it is now. Aside from musicians, there is a massively underwhelming number of people who actually take the time to listen to music and try to understand what the lyrics are really saying, what message is being conveyed and how each instrument plays it's part to attain the communication of this message.
I also feel this is part of why metal is so widely unpopular in mainstream music. The vocals are harsh and aggressive (NOT angry or violent, these are different things) the messages tend to be very indirect and often "taboo" as well. The guitars are loud, piercing and aggressive. The bass and drums are loading the bottom end up and can have a very rhythmic and tribal sound to them. All these things together make a sound that is abrasive to the ears at least initially, add on that you can't listen to most metal and just know what the song is about and yeah... way too complicated for 95% of the people in this world.
Music, especially lyrics, in the mainstream is about what's catchy, what's easy to hum or sing to, money, women, drugs, clubs, bling bling and being a gangster. Anything other than those things and you're in for a rough time typically.
EDIT: Another example. One of the most popular songs on the radio by Tool is Stinkfist. I'm not here to debate what genre Tool is, I feel they are progressive metal but I digress... people think this song is about fisting someone. It's not... not even a little.