In this example, the difference between Ezreal E is it gets casted, has a cast time where it has been casted while he's decidedly NOT in the pull, gets pulled, and the cast goes through assuming he doesn't die to the hook/other damage before the cast completes. Given that cast time and channel time are two different things, this is working as intended, so it was left alone.
Flash, on the other hand, is instantly casted. How, then, would you blink out of a Blitz Q with flash after it has already hit, if casting it prior to being hit means you don't get hit, or still get hit AFTER blinking, and casting it after being hit should be impossible while being transported to him? Shouldn't be able to, so it was fixed.