You don't have to go through it over and over for the most part, IIRC the most you ever have to go through any section is 3 times, and there's only one section like that. and of course it's designed so that you can use those later runthroughs to improve your time, find different ways to get through it with your new items, etc. So all in all, the "OMG you have to go through it multiple times" complaint doesn't make much sense to me.