Respect should first be given to the truth of suffering, to the truth of the cause of suffering, and the capacity of the dhamma to free you from that. Why? Because if you have no respect for the capacity of the fire to burn you, or the balm to sooth you, then you will only continue to burn.
Respect should be given to the Buddha, as a practitioner who accomplished something very profound and difficult, something noble and worthwhile, and then chose to share the wisdom of how he accomplished that with us all. He should be respected as someone who can teach us valuable lessons. When we see a statue or an image of the Buddha, we respect what it represents, the accomplishment and nobility of what was conquered.
Respect should be given to those serious practitioners who have set themselves out to follow the path laid out by the Buddha, to take it upon themselves to accomplish what amount of that great work that they can. It is hard work, arduous work that requires diligence, and is worthy of respect.
If we respect these good qualities, we will be likely to emanate them. If we do that, we may become free of our suffering. It is good to do so.
This is why.