My question is, besides 'regulating' the rate of blocks found, what is the role of difficulty? The emergence of ASICs will probably cause a great increase in difficulty this year. Does difficulty also reinforce the security of the network? I find this interesting because if so, I'd say the bitcoin value can be expected to go up with the prevalence of ASICs since they will lead to a more secure network and might attract more investors.
I think the difficulty affects the security of the system as well, such that the more difficult it is to create a block, the more difficult it would be to break it. Not 100% sure about that though.