First, let us turn to the use of incense. Incense also has a long history in many religions, including the Jewish Temple. Incense has several uses: the smoke symbolizes prayers rising heavenward, it has been a costly (sometimes lovely) offering to divine honor. Frankly, it has also been used as a practical cover for the smells of ancient sacrificial cults or for musty church buildings.
Before Constantine, incense seems to have been avoided by Christians because of the association with the pagan emperor cult. After the fourth century, Christian use of incense seems to have slowly increased, and in the medieval Latin Church, it became associated with scholastic theories of the Mass. For this reason, beginning in the sixteenth century, Anglicans tended to abandon the use of incense in worship. Despite occasional exceptions, incense did not make a come back among Anglicans till the nineteenth-century Tractarian and Ritualist movements. Since then, some Anglicans have seen incense simply as an aesthetic embellishment; others have viewed it as a serious affirmation of spirituality.
There is also another consideration regarding incense. Some people (including the writer) may have allergic and asthmatic reactions to strong scents including incense. A number of Anglicans have told me of such adverse physical reactions. So if a cleric or congregation wants to use incense on occasion, people should know in advance, and there should be another service without incense for those incense harms.
Secondly, let us and consider bells. Bells have a long history in many religions. They have been used to get attention, to express sorrow, to express joy, and to mark especially significant moments. In Western Christianity, the Sanctus or altar bells date from the Middle Ages, and their increasing use seems related to the history of certain medieval theories of the Eucharist. They have been rung at several points, particularly at each "holy" in the Sanctus and before and after Christ's Words of Institution. Some Anglicans over the centuries have opposed the use of altar bells at the Eucharist. Some have simply viewed them as a disruption in quiet services. And some Anglicans are fond of altar bells as audible reminders of important liturgical points.
To conclude, smells and bells are adiaphora or optional. They may be uplifting for some people in some services, or they may be distracting to some. But ultimately, they are optional, and their use or omission is not necessarily an expression of doctrine.