Dear Calvin,
I have been working through some of this exact subject with a couple of other guys in the last day or two, it's odd that you asked about it but is really dead on. Sometimes I will install a glued on tip to my arrow but not always. If I do that I do fill the hollow part of the shaft with a dowel and glue to get the weight forward effect without even seeing it. You can add sand or anything else to get the weight weight right.
I like to make a removable fore shaft because it can come out if you do not get complete penetration. If the foreshaft comes out and the main shaft drops away the wound opens up and the blood trail is better. I have also never broken one of these arrows that drops away because as soon as it hits a sapling or tree, it is yanked apart, is out and the shaft is on the ground.
Another reason for a separable foreshaft is that you can make them more quickly and they do not have to be dedicated to the arrow. You can make up a dozen pile ends and if you want to smack a rabbit or squirrel with a blunt you can be ready in a minute. In other words you can have three good arrows and several types of points plus youcan have sharp points ready to install. You can sharpen points more easily by having a shorter piece of wood in your hand and you can use the foreshaft as a handle. I can come up with some other reasons but those are some good ones.
Take care, Murray