Understand that the Orange Line is setup like a light rail line. The busway has grade crossings with other streets much like a train, except unlike a train it doesn't have the flashing red lights or crossing arms. That led to a considerable amount of accidents in the first few weeks of operation. That's when the speed limit at intersections was lowered from 25 mph down to 10 mph.
Now that drivers have more experience with interacting with the busway it seems like a good time to raise the speed limit back up to 25 mph (not 45 mph). I doubt Metro will ever go faster than that, it's just too dangerous (a bus hitting a car in a crossing is a much more violent crash than a train hitting a car).