Low impact knowledge

I came across the old rhyme of Lester Moore.  

Here lies Lester Moore, 

Four slugs from a .44, 

No Les, No more.

Supposedly from his tombstone Boothill Graveyard in Tombstone, Arizona.  

I think I had already encountered the poem before, but I certainly saw it when I visited Tombstone with my Aunt June and Uncle B on a trip from Los Angeles to Tulsa, Oklahoma when I was twelve or thirteen.  Wikipedia says the headstone is a later hoax.  That is as it may be but sometimes it is comfortable accepting that some things ought to be true.  

The thought which occurred to me as I read those lines last night around midnight was that I know these lines.  I have known them most my life.  I have always read them as witty but this is a nugget of knowledge which seems to have no salience or utility.  I have never needed to know them.

I could be ignorant of the poem without, I suspect, any noticeable degradation of status, epistemic completeness, empirical or reasoning loss, or cognitive utility.

I enjoy the lines and am amused by them but they have no apparent utility.  Rather like an appendix.  

Which prompts the thought - Just how much do we know and decorate our mental landscape with, which contributes nothing to status, epistemic completeness, empirical or reasoning loss, or cognitive utility?  And if it serves no utility, why do we retain such knowledge?  Why does it appeal to us?