Forms are an important part of many (not all) martial arts. Mostly, they are still found in the more traditional martial arts, but some of the martial arts with a more competitive approach have distanced themselves from them.
Forms are a way of catalogueing and teaching all (or most) of the techniques found in a martial system. Originally, these techniques were battlefield-tested, were found to be valuable, and were then kept as part of a system. Forms were created as a way of organizing the techniques into a curriculum so that it can be practiced systematically, as well as taught to others systematically.
Not all forms today consist of battlefield-tested techniques. In our modern day, we often do not have the opportunity to exhaustively test our techniques in a real life-or-death situation. Some of the forms that have been created in more recent times, then, may consist of techniques that are less reliable than those that were created in older days. Especially, in my opinion, many of the forms that are created with an eye to modern forms competition, are pretty worthless. That is, they are both pretty, and worthless. Fun to watch, very athletic, but very little of value when it comes to reliable technique.
The older forms were created from techniques that were proven effective, but also took into consideration other elements in one's surroundings. This would include geography, types of clothing worn, weapons used, armor, social norms surrounding combat, etc. Because of this, not everything in the older forms is still effective today. What is important to recognize is whether or not your forms are alive, or dead. A living form has techniques that are still useful. A dead form has techniques that are either no longer useful due to societal changes, or are simply flashy but useless, meant for modern competition.
In my opinion, the practice of living forms is very important, as it enables one to practice the complete system. But forms practice alone is not enough. One must drill the application of the techniques with training partners, so that the meaning and usefulness of the form is fully understood. In addition, some type of meaningful contact sparring is also important to develop the skills needed to deal with an unpredictable and changing situation.
The practice of forms should not be done as an end in an of itself. The goal should not be to give a beautiful performance, but rather to develop the techniques that are found in the form. It is also important to understand that the combinations of techniques that are found in a form are only one way to apply the techniques, and are not the only way. Once one has developed their technique, the application can be done in many different ways.
In short, once again in my opinion, forms practice done correctly is a very important part of training in many martial arts. It is not the only important part of training, however.
michael