The irony is that Apple is in the unique position of getting grief for making their platform MORE secure.
Given the diversity of apps it's hard to make a credible argument that Apple or its users are somehow suffering from the decision of keeping the platform closed. Certainly there have been trade offs, but as a former Palm and Windows Mobile user I prefer having a stable, secure, and user friendly experience. I definitely would not want to see Apple adopting the so-called open, crash prone, insecure experience of Windows Mobile, an experience that is still available to those who are considering jailbreaking their phones.
What security are you losing? You jailbreak yourself, you make the active choice of opening your device. No one else makes it for you. You have the choice of living in Apple's little sandbox and being able to play without any worry.
I on the other hand, like having a little bit of openness and I accept the consequences.
Jailbreaking doesn't affect you if you don't do it. So why worry about it? Or why advocate the removal of this option?