I agree, I reckon for the vast majority of people (including myself although I'm probably one of the more disciplined), the theoretical savings (interest free period, free insurance, points etc) from using credit cards would be far outweighed by the greater amount we are actually spending in the first place, because of the convenience of using cards.
Spending circa $500 on an iPad or whatever is a very different experience if you have to trudge to the ATM, withdraw 5 green ones and go to the shop and actually hand them over, compared to just giving someone a card at the shop in the first place or typing in some numbers on your internet shopping screen with free delivery.
I know a few people who have gone back to cash only because of this and I'm seriously considering the same. Spending money just has a different feel about it with the folding stuff. Not to mention my banker would know a lot less about me, which can only be a good thing!