We are constantly bombarded with pollutants in the air, and undoubtedly, after time, your sense of smell is dulled by constant exposure to pollution. Further, we are always smelling things that are unrecognizable or too subtle for our senses to distinguish. However, consider how closely related are your sense of smell and your memory. The result is often emotional or reflective outpourings unchecked by thought and reason. Quite often, some particular scent can bring back a torrent of memory or emotion, or quickly set a mood.
Incense is a very useful tool for ritual working.
Whether you are burning an incense to make your home smell fresh and wonderful or you are burning it to evoke a higher aspect of spirit, you are burning it to aid in a ritual. A benefit of working with raw or loose incense is that you can easily mix two or more incenses together to obtain a third, equally potent incense. If you work with astrology at all, or if you have had a chart done for you, you could benefit from mixing a planetary incense with a zodiacal incense, to help learn to work with the positive aspects of that energy. You could, for example, burn the two planetary incenses together if you are having trouble working with a conjunction, et cetera. The uses are only limited by your imagination.