Yes There Is a Purpose

With the evolution of martial arts, it is impossible to avoid changes to techniques in traditional forms over time. This could be due to imitation of another individual, incorrect execution, incorrectly remembering the technique, misunderstanding of a technique, overemphasis of a technique (changing the form to match the application of the technique), rushed learning leading to imprecision, or shortage of knowledge in the instructor leading to their own flavour of execution. In fact, I have seen instructors change forms over time to something they believe is easier to execute or "looks better" when they perform. Unfortunately, this takes away some potentially important details in the style.

Instead of changing forms, I would encourage martial artists to think about what they are doing. In my experiences, there are purposes for executing a technique a certain way and for specific hand positions. The purpose could be defensive such as defending an area of the body, striking to a blind spot as a defense (Fut Gar students will be very familiar with this concept), protecting from follow-up techniques, or as a backup in case your technique is unsuccessful. The purpose could be offensive such as setting up your next technique or could a hidden meaning. Before changing a technique, I believe it would be much more useful to ask what all the potential reasons are for doing something a certain way. This not only will help preserve your style but also take you through the exercise of self learning something you have not specifically been taught.

For those that make changes because it looks better...yes, I have heard this reason. An experienced martial artist appreciates a form done correctly and done well. Changing a few moves will not make a difference. Instead of adding flash, it is probably much better to practice your forms until you are known for your precision and outstanding execution.