The speed of the cpu is in /no way/ irrelevant. Yes, you have a refresh limit on eInk but you still have to render the files. Anything to make PDF viewing smoother is good imo, and that generally requires a fast CPU.
As for why need more than 32gb? 'eh, thati s entirely up to user preferences. My girlfriend is more than happy with her ~6gb of space on her nook and just asks me to load new books on it as she finishes.
I have 64gb in my eDGe and keep a huge book library on it as I like having an entire library at my finger tips. I have a couple 10k books. Someone recommends a book and I whip out my eDGe and do a search and 7-10 times I already have a copy