Because people will bitch and moan about it. Austin did just as much and charged for nicer reusable bags, people complained like no other and now i see that some stores are using the craptastic one use plastic bags again. People want to appear like they give a shit about important issues but the second it inconveniences them they quickly stop caring.
Personally i don’t mind doing away with the plastic bags for shopping, and if i forget to take them with me i also don’t mind just lugging my stuff to the car without the bags.