According to my good friend Webster, a rule is an "authoritative direction or statement which regulates the method of doing something." It may just be the mention of authority and the thrill of challenging it that tempts so many of us to break the rules at every opportunity. However, using that old excuse, "rules are made to be broken" doesn't really give any of us a free pass, certainly not in society and to a lesser extent, in our art. And the last time I checked, pleading ignorance doesn't get you too far either.
So how is it that some of the most successful and admired artists are the ones who consistently break the rules? I think it's because they understand the rules better than the rest of us. Breaking the rules for the sake of being labeled a rebel probably won't do much to improve your art. But, breaking or bending the rules in order to enhance your artwork is totally acceptable.
Polymer clay, as a medium, doesn't come with a huge set of rules to follow beyond the obvious safety and baking concerns, which, btw, are on the back of EVERY package of clay. (I only stress that because I find it amazing that so many people think it's fine to bake at a lower temperature for a longer period of time, or to cure clay in a sunny window, or boil and/or microwave it.) However, if you want your artwork to be taken seriously and you want to succeed in doing what you love, there are a lot of rules to learn when it comes to art and design aesthetics. Most of us don't instinctively know these things. We have to learn them. And only through lots and lots of practice and study do we begin to understand what happens when we break these design rules and how to use those results to our advantage. We must understand the reasons behind these rules before we throw them out the window. Personally, I would much rather see a simple piece of artwork done well and by the rules than an elaborate piece with no regard given to design concepts or finishing techniques. Read everything you can find about art and design, take classes when possible, study work from artists you admire, practice until these things become second-nature. Begin where you are! Don't be in a hurry to break the rules. Before you run with your clay blade, you need to walk.