"Why did it took them so long?" The idea of a stablecoin is in fact several years old, and dollar-pegged tokens for example, USDC is already available on some cryptocurrency exchanges and users will enjoy 99% off the trading fees on USDC trading pairs on BTC, ETH and USDT from October 15 to 22 , 22:00, 2018 (UTC+8). You may find the news here https://news.kucoin.com/en/kucoin-will-add-usd-coin-usdc-market/.
RE: Another USD-Pegged Stable Coin, USDC, Issued By Goldman Sachs' Circle