Quilting on a quilt can make a big difference in a quilt. If there is to little the quilt looks naked and boring. I am of the opinion that there is never to much quilting, but I am sure that there is a quilt somewhere that has to much quilting.
When quilting myself I prefer to hand quilt.
For one thing I have not learned how to machine quilt. I do not want to just start without someone guiding me. What if I put a quilt under the needle and the bobbin explodes on the back or something disastrous happens! I just don't want to put a lot of work into a quilt to mess it up machine quilting. Also, I do not want to hire someone to quilt it for me. I am sure that they all do a wonderful job (I have seen some wonderful machine quilting), but that would mean that I did not do the entire thing myself.
Hand quilting is one of my favorite parts of completing a quilt. My hands like to be a part of the work. That may sound strange but when machine sewing my hands guide they do not do the work. There is just something about making something by hand. It relaxes me.
Quilting is not for everyone. It takes time and patience. Quilting a baby quilt depending on the amount of quilting I am doing can take me (if you put all of the free time I find together) anywhere between a week and a month continuously quilting. It often takes me longer because I quilt in my free time, usually while watching TV.
Many people want something now. For these people machine quilting is probably the best. You can have a quilt finished in a weekend.