Even for well-read people there might be something that was hidden from their sight, or a new aspect on a well-known subject is depicted.
Current applications of processes, especially out of the field of arts could be interesting.

I must admit though, that the classical technical article, now with the combination of text-book and internet forums, has lost much of it's appeal in the sense of teaching. However, in the sense of teaser technical articles could be interesting for beginners.