Fan fiction: artistry or cheap pandering?

So, I've recently started reading a remake of a classic.  I haven't finished it yet, so I'll refrain from mentioning the title yet.  However, I'm noticing that there are quite a few classic remakes out on the market.  I'm wondering how everyone feels about this though.  Should the classics be considered untouchable?  On the one hand,  I feel a good story line has the right to be told regardless of the whether or not the characters or theme is one that was created by someone else (as long as you give credit, where credit is due!).  Such as the Sherlock Holmes stories, which Sir Arthur Conan Doyle "borrowed"  (for lack of another term) from Edgar Alan Poe.  On the other hand it can be said that this an example of a "lazy" author, not taking the time to create a completely original piece?  I guess it can be summed up like this:  Fan fiction, is it artistry or cheap pandering?  For me personally, the jury is still out.  But, I would love to hear anyone else's view.