Why does Rengar's E still have a cast time when used mid-leap?

It was about 2 years ago when they gave Rengar's E a cast time when used mid-leap. The reasoning for this change was to "give players more time to react." However, all it really did was make Rengar's one shot combo needlessly difficult. I just don't get it. It didn't make any sense then, and it doesn't make anymore sense now. Even experienced Rengar mains miss their bola all the time because even though they aimed it correctly it whiffed over their target's head. Either because they moved in a different direction or stopped moving in general. It's just frustrating, and I would love to see this cast time done away with. As I said before, it makes to sense. If anything it just makes his combo feel clunky as hell, and for no good reason.