I'll take out a BIN with a quid if I believe the item wouldn't reach that price anyway. I don't want a bidder who doesn't know any better buying the item from under me. Most of the time with a bit of price research it works out for me. That's the view of a buyer.
Saying that, I've also bought many items on BIN as an early bird when of course the seller doesn't know any better and has listed a bargain.
As a seller If I was bothered about the selling price I'd start the item at a decent enough high price with a BIN slightly more to put off bidders even bothering.
So, neither good or bad, just part of the Ebay way.