Sure, for the most part it is. However, you use that "paper shredder" only occasionally in limited instances when you are getting rid of something in Passbook, whereas the default animations for unlocking the phone, launching/closing and app, opening/closing a folder, bringing up multitasking/recent apps view, etc., are used on a constant basis many times during any given day by most people.
If they like the animation and think it adds "cooler" effects, then even if it is somewhat slower--essentially longer lasting--than before, they can surely do it for aesthetical type of reasons. Heck, they have the genie effect in minimizing windows in OS X--it looks kind of fun/"cool", but doesn't really do anything useful and takes somewhat longer than a simple non-"cool" scale minimize effect.