Old question, but anyway... I hope it is useful to someone
My understanding is that the flavors of meat and vegetables pass better to unsalted water. So, if you are keeping only the broth, it is better not to salt it. If you are eating some of the vegetables, meat or fish and you don't salt the water, they will be tasteless.
On another hand, if you salt the broth, later is difficult to know how much salt contains your recipe.
When I cook, I estimate the serves that I am getting and I use a level teaspoon salt every two serves. So, I never salt the broth broth. I make the broth and I freeze it in portions. When I use a portion of broth on a particular recipe, I salt all together based on the number of serves I am getting.
Despite not salting the water, I eat the meat or fish and carrots. Cook the carrots in one piece and the vegetables that you are going to waste in tiny pieces (I use the mincer). This way you increase the surface contact between the vegetables (except carrots or other you like) and the water and they should release better their flavor. You also reduce the cooking time.