Yes, read this. People are over-reacting and not reading what Coinbase is saying. There is nothing negative about it.
This is an additional, and OPTIONAL feature they are trying. There is still the normal 24-hour rolling limit, where you can buy bitcoins for the current price. If they have reached the limit for the day, you have the option to put in an order, and receive the coins at the price when more funds arrive. If you don't want to do this, you can just cancel your order.
It isnt optional though.. you cant click buy without agreeing that you may get a 5 day delay whereas before you could just click until it went through right there. im not sure if the auto-buy thing helps it become more optional or not