I like my XM for the same reason I like British cars. they supply me with off-beat, non-mainstream enjoyment. I can listen to stuff on XM that I just cant get on the pathetic top 40 radio stations around here.
Bluegrass, folk, deep cuts, old radio shows, comedy, and lots of other goodies.
So, hide it in the glove box so you don't have a chunk of modern, digitized plastic breaking the lines of your classic, and enjoy being able to listen to the kind of programs that woulda come through the crackily AM radio that the original owner would have had in it.
Or whatever floats your boat while your out cruising, without the ten minutes of stupid ads between every two songs.
Consider it an "experience enhancement"