This is a good question. Don't be surprised if I try to answer it on more than one occasion.
I came to fiddle tunes as a guitar player before I ever knew what a dulcimer was. Part of the attraction is the same as for any folk music. It amazes me that music dating from the seventeenth century or earlier can still resonate today. And somehow I feel a connection with people from the past by understanding the music they played, even if I hear it through modern ears. But whereas some folk tunes require the lyrics to be interesting, fiddle tunes obviously don't, so those of us unhappy with our singing voices might be drawn to fiddle tunes specifically because they are instrumental.
When I first began studying fiddle tunes,I found, as did Strumelia, that they all sounded the same. The only ones I couldeasily recognizewere those that had become standard songs, such as "Arkansas Traveler" (which, like all kids, I learned as "I'm sweeping up a baby bumble bee"), "Eight of January," (the tune for which was used in the pop/rock song "Battle of New Orleans" in the late 1950s), or even "Sailer's Hornpipe," (which my animated buddy Popeye taught me).
But the more I listened and studied, the more I learned the nuances and beauty of each song. "St. Anne's Reel" is really pretty. "Whiskey Before Breakfast" really bounces. "Red-Haired Boy" and "Salt Creek" really surprise with that VII chord.
So for those of us without good singing voices but who want to play traditional folk music, fiddle tunes offer a large repository of material.
There is also a technical reason for playing fiddle tunes. As I learned when trying to be a bluegrass guitar player, you can't fake it with fiddle tunes. Your technique has to be up to par to play these songs at a"danceable" speed. Just practicing them, in other words, helps develop your technique. In fact, a guitarist friend of mine now living in Birmingham who was the reason I took up mandolin (he was just way better on the guitar than Iand also had a killerSanta Cruz dreadnought) has since abandoned bluegrass, but still warms up by playing a large repertoire of fiddle tunes. He claims he gets the same workout as playing scales but has a lot more fun.
One final reason to play fiddle tunes: lots of people know them. I got together with a neighbor recently and while our kids played in the yard she grabbed her banjo and I grabbed my guitar. We hadn't played together inmany a moon, but we still both knew "Old Joe Clark," "The Road to Lisdoonvarna," "Jerusalem Ridge," "Red-haired Boy," "Blackberry Blossom" and so forth. Fiddle tunes serve a social role, since they represent a common repertoire that you can learn on your own and then play with others. And they are far less repetitive than the 12-bar blues!
I've written this before, but my original introduction to the dulcimer came about 18 months ago when I was surfing YouTube for variations on fiddle tunes to improve my guitar playing and found Stephen Seifert playing "Whiskey Before Breakfast." My jaw dropped and I became obsessed with the dulcimer. That something so pretty and so danceable could be played in such an inventive way on such a simple instrument is still astounding to me. When I develop a version of that song on my own dulcimer, I will indeed have reached a milestone.