Greetings in that Divine and Most Precious Name of Our Lord and Savior Jesus Christ!
The purpose of physical worship such as prostrations, incense, icons, buildings, books, chants, etc etc is not to get a person "closer to God" in the sense that proximity to God is limited by these. God is not limited by Incense, however, as it has been explained, these kinds of physical worship are deeply ritualistic and symbolic of the deeper, underlying meaning and intent. When a person offers Incense with their prayers, or prayers before the presence of Holy Icons, or performs certain prostrations or recites particular written prayers, these are symbolic of the underlying inner intention of that individual to get closer to God with prayer. These should not be assumed to "force God's hand" or to earn God's Grace or favoritism in matters of our lives, that is not prayer. Prayer is communication with God, not a wishlist or a complain department. As such, physical attributes of prayer are highly symbolic of the inner feelings of yearning to get closer to God and to communicate.
Yes, incense and icons are sensory reminders of prayer, and they serve this function, but it is deeper than that. After all, God can speak for Himself by His own power, He doesn't need incense to communicate with us, and we don't need it to remember Him, He is not merely a memory which we recapitulate on like the family photo-album, rather we can always know God in the present tense. However, still there is a need for these symbolic actions and gestures, not merely to remind us our capture our attentions, but to manifest the deeper realities of our intentions.
If I want to communicate with you, I have to call you directly on the phone, or actually type up this email, or tap you on the shoulder and say, "hey" but I can rarely achieve good communion telepathically. In other words, I actually have to do something in verb sense, otherwise I am just thinking about communicating. While we can communicate with God beyond physical, because He Himself is beyond physical, we still remain physical beings during our prayer. This is why we use physical gestures and tools to accompany our prayer, not because it benefits God, or enhances God's Grace, but because it benefits ourselves, and enhances our own sense of awareness.
God is beyond incense, but we are not. God's Grace is beyond incense, but we must show God in our symbolic actions that our intentions are sincere. In using the incense or the icons, we are showing God in a physical way our intentions. God knows our hearts, but we ourselves need to use these physical gestures to keep our attentions focused. God doesn't need them, we do. That is what symbolism is. Symbols are objects or actions which convey and communicate deeper, underlying, and hard to explain meanings. It is further deeper than just trying to maintain a sense of awareness, rather like any kind of sport or dance, the purpose of the gestures is in the gestures themselves because these are the actions and activities. Prayer is not limited by incense, but incense is definitely prayer in action, symbolic of our own hearts and intentions acting on God.
We don't worship God with incense, we symbolize our worship, but the symbols should not negate the power of God, and neither should the power of God negate the potency of the symbolism. Actually, these cooperate. The symbol is the manifestation in the verb sense of our worship, of our communicating efforts, of our prayer.
Let me ask the flip side, what really is the harm with incense or icons in prayer?