One of the main reasons to use Coinbase was that they didn't have fees. Now looks it's just more one online wallet and there isn't special reasons to use it anymore... And there is that issue with gambling sites too. Maybe they had to add fees as they need fast transactions and without charging users they could have losses.
I think that people mainly use it for its purpose as an exchange. It's quite convenient for people who are not actually much good at trading and just need something obvious to buy and sell when they want into a "wallet".