You can do rapid morphing without getting as tired, as well as just morphing part of your body to save energy. So if your leg gets broken in battle, you can just fix it instead of morphing a whole new creature. That would leave you vulnerable in mid morph, and require more energy.
Also if you need to show someone the morphing process for some reason, and don't want it to look so bad, you'll be able to make yourself look like something appealing instead of an eldritch abomination.
