"junk DNA" a useful term or not?

I am jealous. Here in Anerica, you can die of frustration trying to find a science program with any depth. And that's with 150 channels!

Yes, but the terminology was never useful, to answer your original question, and I guess I would argue the term should not be used in any context. 'Junk' implies a lack of function for a sequence (repetitive or otherwise) on the singular criterium that there has been no 'function' demonstrated for it - as yet. It is therefore a negatively defined 'catch all', waste bucket category that is delineated only by our substantial empirical limitations.