The difficulty with pre-existing conditions is that if the insurance companies can't reject people because of them, people will wait until they need insurance to get it. Since the insured population will be much more sick than the population as a whole, insurance will be much more expensive (or much worse in quality). That will cause some people who need insurance not to get it, and for the people who aren't sick to shy even further from it.
The solution is requiring everyone to pay for insurance so that the pool of insured people is as large as possible. My personal preference is either a single payer, or multiple payers who are all registered non-profits and required to keep a very high Medical Loss Ratio. The individual mandate will do this to some degree in the US, but it may still be cheaper to just pay the fine than get insurance.
I think the problem with pre-existing conditions is that insurance benefits are misaligned with the risks they're supposed to mitigate. The policies are written to cover care month by month rather than condition by condition.
Say I buy an insurance policy to mitigate the risk of treating cancer, should I develop it. I would like a contract that said, "The average cost of treating this is $X and its incidence is %0.Y so if you pay us $X * %0.Y + Profit, we'll agree to pay to treat you if you ever develop it."
Or say I already have cancer and want help treating it. I'd like a policy that said, "It might cost you $10,000 or it might cost you $500,000 to treat this. But we'll offer you the average cost split into payments over several years, and we'll absorb shocks in the price for you."
It seems bizarre to me that health insurance is sold the way it is. It's as if I had auto insurance that paid for repair work to be done that month--whether or not the accident occurred while on that particular contract.
The solution is requiring everyone to pay for insurance so that the pool of insured people is as large as possible. My personal preference is either a single payer, or multiple payers who are all registered non-profits and required to keep a very high Medical Loss Ratio. The individual mandate will do this to some degree in the US, but it may still be cheaper to just pay the fine than get insurance.