Physicists use models in order to help themselves and observers understand phenomena and theories in a better manner. Physics deals with various very complex concepts and theories, and without the use of models, it would be very difficult to translate those ideas to those who want to learn it from an instructor. In simple words, the most basic function models serve in physics is to help students understand a physical concept.
Physics involves a number of complex processes that require explanation through detailed scientific modeling, which could be operational, mathematical, graphical and conceptual, depending on the objective. Another advantage of models is that they can be easily manipulated to simulate and roughly symbolize how actual natural and physical processes work.
Furthermore, physics frequently discusses multi-dimensional concepts, which are very hard to understand for beginning students and people with little knowledge of this field of study without the use of models. As a matter of fact, even advanced students would have to strain hard to get their heads around such concepts.
Complicated concepts such as the theory of gravitation and special and general theories of relativity would not have been understood so widely among students of physics without the use of models. The importance of models become far greater at the quantum levels, where teaching concepts is an even bigger challenger.
In physics, models are frequently used to describe atomic and molecular structure, and are also frequently used by other branches of natural science, such as chemistry and biology. Models are even used in other walks of life, precisely for the reason that these graphical and visual learning aids make communication far easier than what it would be with words.
Physicists use models because they make their lives a lot easier and make it much more probable that students would actually be able to learn something.