There certainly are plenty of minor tunes, but it is a statistical fact that the British and Irish traditions favour the major key for fiddle tunes. And, also, the arrow of time points inexorably towards the major key; if you clasify tunes according to the ealiest date they appear in publications, or MS tune books, you find that the proportion of minor tunes is greater among the earlier tunes.
    A very obvious example is this: think about the hornpipes you know(if you know any), as opposed to the jigs and reels.I would put good money on the fact that very few, if any, of the hornpipes will be minor:but plenty of the jigs and reels will be. This is because the hornpipe was a musical form that really developed post 1700 say , by which time the ascendancy of the major key was well established, in Ireland as in Britain.Fiddlers were mostly naturally creating in major keys by then.
   I have just had a glance at the last recording I made, which was collection of traditional Cumbrian tunes. There are 31 tunes on the CD, and all but two are major. That is about par for the course.Of course, if you selected tunes for beauty and sadness, for example, you would get a higher proportion of minors.