But how many people who can't afford comprehensive coverage do you suppose are going to fork over for non-criticals like flu shots in the first place? Routine preventive care is the first casualty of that sort of model. I'm certain I wouldn't have wound up getting diagnosed with the genetic disorder I have as early in the symptomatic stage as I did, had I not been fortunate enough to have excellent comprehensive coverage (perk of working for a large university) by that point in time. Because my symptoms didn't seem particularly serious, they were annoying rather than disabling or painful, and besides, I was still 'young and healthy' (so far as anyone knew at the time), so why spend money we didn't have getting them checked out? Of course, even if I had gone ahead and paid out-of-pocket to have them checked out (which, in fact, by the end of the process would've easily met a high deductible--the MRIs, neurological workups etc.), then I'd still have been screwed once the diagnosis was made, because then I'd have a "pre-existing condition" in the eyes of any future insurer, while meanwhile high-deductible "catastrophic" would no longer be practicable, given the ongoing costs of monitoring and treating the condition.
I chose to buy my house, I chose to buy my car; I didn't get to choose my genes, and I could never afford to pay my own medical bills, let alone my dependents', if I hadn't been able to afford comprehensive coverage by the time fate decided I needed it. I know from corresponding online with other people with my condition--at least, the ones here in the US--that they haven't all been so lucky in their insurance situation: some are facing huge medical debts; some are unable to find an insurer who'll take them, because of how much they're going to cost; some have put off needed neurosurgery because their insurer won't cover their preferred neurosurgeon's costs (insisting on a neurosurgeon with experience in the specific operation you require can be expensive). And as far as I can tell, your response to situations like theirs seems to be, "It's your own damn fault for not having had both the money and the foresight to realize that something like this could happen and make sure you were covered." Unless I'm completely missing some implicit qualifications that were meant to follow from your ideas.