Removing the timer on the minigame makes sense, but the held notes? C'mon... It was probably the most fun hacking mini-game to date and it's being dumbed down to the point where it's no fun?
The only reason I could see for its removal is that it might be confusing to some players the very first time they try it. Which, together with a time limit, might be somewhat annoying. But the mechanic is fairly common in a variety of games and, without the timer being involved, could easily be displayed with a simple informational key on the UI. () - press ()==() - press/release.