Personally I have mixed feelings about this.
In principle, I agree, but in practice I find that these types of threads do little to stop the endless cycle of repeated suggestions. Let's face it, people get excited about a 'new' idea that isn't implemented yet, then they post to let the world know about it. Perhaps after the excitement has faded they will think to search, or read a stickied thread.
In the worst case, they give people some ammunition to say READ THE STICKY NOOB, rather than take a small amount of time to respond politely in the manner of 'thanks, but this has been suggested many times before'.
I don't personally feel that the quantity of repeated suggestions are overwhelming, so I would tend to leave it as-is for the small risk of increased negativity towards over-excited newcomers (who should always be welcomed heartily), especially as I don't think it will help as much as it theoretically should.