The gist is that Portland drivers couldn't stop hitting crucial safety infrastructure (proving its necessity) so PBOT gave up on it.
As one of the commenters pointed out: Since a pedestrian/bike fatality costs PBOT nothing and replacing a concrete planter a car has demolished costs them more than nothing, to balance the budget they're going to go with more pedestrian deaths.
TLDR; They didn't actually expect them to work. Every time they get hit, they move and they require a crane or forklift to put back into position.
Perhaps they should double the weight of them so they're less likely to move when struck.
If drivers couldn't stop hitting the planters, then the planters aren't the problem. But hey, at least Portland is accomodating to maniac drivers.
Not every intersection should or needs to be replaced by a roundabout, especially on local lane intersections where speeds are already supposed to be low. They take up more space, are more expensive to maintain (than a stop sign-controlled or uncontrolled intersection), and are also less convenient for bikers as well as cars.
Stopping with 30 kph puts a pressure of over a metric ton via the seat belt on your body for a short time.