Having a small, medium, or large tree attached to your test will help you get the most from your AncestryDNA experience. Whether you started your DNA journey to find out where in the world you came from, or to find a new cousin, attaching a family tree gives you added power when it comes to making connections. Watch the following video to gain insight into the benefits of having DNA + family tree.
I agree it is good for folks to associate their DNA test with a tree. I would add that you can search your DNA matches by surname and/or location. This can be very valuable. Also, you can see if you have “shared matches” with a particular person who shows up in your DNA results – also quite a valuable tool that is probably underutilized.