Patents are assets and there is no reason they wouldn't add value to a would-be licensee - even just being able to say a product is patented often has at least some small value in itself. And, where there is an issued patent, there is more certainty that a product is patentable.
Of course, how much value they would add depends on the patent, the market opportunity, and other factors. And its also important to keep in mind that a patent in itself will not suddenly make an invention licensable, per se. A patent is no end all be all answer, you still need a good, marketable product that the patent protects.
If you are looking for a licensing deal, patents can also expand your options. Some companies won't be willing to talk to you without one and others simply won't be willing to sign an NDA.
