Some time ago, I don't remember when, I prepared a web tips page on this topic. I must have forgot to post the link:
http://gregmaxey.mvps.org/word\_tip\_pages/classic\_wordart\_in\_word2010\_2013\_documents.html
Greg, your tip to add the Compatibility Mode Quick Tool icon is the key to making this totally simple. However, the challenge most seem to have is how to get the campatibility mode document without having an old copy of Word 2003 installed. It's simple.
First, here is a screen capture of your tip to add the WordArt icon to the Quick Toolbar:

Now, to get access to the aold style word art tool, open a new document in compatibility mode by going to File/New/My templates and then selecting "NormalOld.dot". You can then copy any stuff you have in a 2010 or later document into this one as well as
create and edit WordArt per the old 2003 capabilities, including gradients, shadows, colors, etc. etc. See the screen shot below:

Below is the look of the good old 2003 word art formating dialog box :):):)

After editing the NormalOld template file and saving it as a regular, non-compatibility mode .docx file, the word art remained just fine. Although the OldWordArt quick tool icon grayed out in the .docx mode, I could still edit the word art per the old 2003
method.
Hope this helps.