Privacy is a necessary feature in my opinion, but why hasn't Monero become a main coin?
Bitcoin is the main coin while other coins are altcoins. People also know monero too. Monero is the 28th on the list if marketcap is used for comparison. It is having a marketcap of over $2.6 billion. Which means it is a good coin.
But if you expectations about the coins is not up to what the marketcap is, it is good to know that most people that are into crypto do not care about privacy, they care about investing and making profit from the coin they invested in.
I don't know how they put up with full transparency on all their bills, the only explanation I can think of is that they don't even think about paying their bills in BTC