If you look at the two clubs with the best home gates (Sheff United and Bradford), they are both cheaper.
It's about balance. If you put prices up to £50, you'd probably still get 5000 paying that, which would probably generate a bigger return. But we don't want that, because we all know there are advantages to be had by having more people in the ground.
I don't have a massive issue with matchday prices, just wish people would stop perpetuating this myth that they are cheap for L1, because they just aren't