You mean you have not encountered players who eschew the "new stuff"? Really?
Well, there are several reasons why people would avoid 'new' tunes. There's a whole range of tunes that do not begin to sound like traditional tunes and people would avoid them because they perhaps don't enjoy the form.
But that's a completely different story, even allowing fora bit of hyperbole thrown in for effect, from what you said:
if a composer's name can be attached to a tune, it must be avoided for its lack of obvious puredroppiness. As if the majority of a piper's repertoire must (and should) somehow spring (anonymously) from circa 1790-1820.
A good tune will be taken up, no matter how new and how wellknown the composer.
I recall going over my Martin Rochford tapes during the late eighties. Martin was considered a great source of 'old tunes' and rare tunes at the time. And he was. But during my trawls through some of the outposts of his repertoire I came to realise his reason for playing tunes was not the ages or pedigree of the tunes but the quality of them. In fact I found his most celebrated party pieces were all (relatively) new compositions and came from Junior Crehan, Ed Reavey, Seán Ryan, Paddy O Brien, Paddy Fahey, Frank McCollum, Larry Redican, Bobby Casey, Paddy Canny, Breandan McGlinchey, Tommy Coen and other composers who were, essentially, all his contemporaries. This opened my eyes to traditional music not being about old tunes at all. It's about getting and playing the good tunes.
I don't think this has changed, I hear tunes played all the time by the composers I mentioned above and many put together by people who are now playing, people of my own generation and people of younger generations.
So no, in general I don't believe there are many people avoiding 'new' tunes at all, quite the contrary. I believe musicians in general are trying to expand their repertoire and that can come from old sources, printed or recorded, or from newly composed material. It doesn't really matter, you take them where you find them. But in general, a good tune will be recognised as one and will be taken up with a vengeance.
And if there are people eschewing new tunes just because they are new, I don't believe for a second it's a widespread trend or even an undercurrent.