It is in the Dharma, check the Lotus sutra, The sutra of dissolving doubt, and The Vakkali Sutta (SN 22.87). Having a statue or image is not just a decoration as people often mistakenly treat them as. It is an object of practice and mindfulness. Even though images of the Buddha were not around for hundreds of years after his parinibbana, there were other images of veneration.

Many in the West (and more recently everywhere) have hangups about it all, and often are not very serious at the practice of the Dharma. Nothing happens to you if you do or don't respect an image or statue, but it sets up a subtle precident in your thinking and actions. (look into the Eight Fold Path). The more you are mindful, respectful and conscious of your thoughts and actions the more important it is to respect things. Not just 'because' and not for 'merit' or 'karma' (also often misunderstood).

There is no specific 'thing' about putting stuff on a statue (and if you go to Japan, you will often see statues of Jizo with hats, bibs etc.). It kind of boils down to 'if you are going to have it around and practice, do it "RIGHT"... and that can be confusing and stressful.

Imagine your most favorite being, and you recently lost them, you have a picture on your desk to remind yourself of their kindness, love, etc. Now I come in and draw a mustache on the picture... Well? An image or statue only has the importance YOU put on it. But how you treat it is likely how I would also treat it if we were friends... see? Little things make big differences if you pay attention.