Coins or coin money is often underestimated by some people because it makes heavy even disturbing in the wallet. Indeed if you think in passing, the coin worth 100 rupiah, 200 rupiah or 500 rupiah seems not too useful. So if we get scattered, we do not feel lost anything, any money is still valuable money.
Most people, too, are still fond of using cash transactions with banknotes and coins. Although it is reported that non-cash transactions are increasing, but that number is still far from the total population of 250 million people. Non-cash transactions of Indonesian people have not been 10% of the total population of Indonesia.
This means, in our daily life, still need cash, be it paper or coins. Small transactions like paying for parking, or returning shopping at a stall, sometimes we find there coins there. Eventually, the coin will fill the wallet more and make it look thicker.