One thing I�ve never really understood is people who only listen to one genre of music. Even at my most dogmatic (and I really was a little asshole about such things, for longer than I care to mention), there were usually at least three or four different types of music I would deign to listen to. I�ll go through phases where I listen to a lot of, say, country, but I�ll still through some other stuff into the mix, just to keep things interesting. And that, for me, is the key. A steady diet of anything becomes tedious after awhile.
I�m not saying there�s anything inherently wrong with limiting one�s musical horizons, of course; that would be as foolish as insisting that everyone share my taste. (Of course, the world would be a better, happier place under such circumstances.)* But I do see it as self-limiting. If something is A and A only, it�s missing out on options B-Z, which can cover a lot of interesting territory.
Also, hopping genres allows one to hear the music in a new context. Playing Hank Williams next to Ernest Tubb next to Lefty Frizzell is fine, but playing �Lovesick Blues� next to X�s �Beyond and Back�, let�s say, or �See the Sky About to Rain� by Neil Young, or maybe Otis Redding singing �You Don�t Miss Your Water� (just to pick a few possibilities off the top of my head � I don�t know that they�d actually work together, but in my mind they do) is going to show each song in a different light. They all have some similar elements; they may not be obvious at first glance, but when played in that context they�d become clearer. At the very least, you might re-examine them.
All popular (western) music of the Twentieth Century (and the 21st, so far) is an amalgam of various predecessors. That�s what�s so cool about it. It�s a little of this and some of that, and suddenly you�ve got something new and exciting. Rock & roll is country + blues, more or less; R&B and soul came from a mixture of blues and gospel; country is based in part on English folk music and blues. And on and on. I�ve heard the argument that jazz is totally original, but my understanding of it is that it sprang from the blues, at least partially. The blues, in turn, originated from a mix of African music and old hymns, according to at least one theory.
These are all rough approximations, of course, and I�m not trying to downplay the work of the innovators who first thought to create new sounds from a combination of older ones. I'm over-simplifying things to make a point: there really isn�t any music that�s 100% �pure�. Everything is informed by everything else. So to say �I only listen to_________� is to miss the big picture, to my mind.