Why excluding pre-existing conditions isn't the good part of Obamacare...

I have heard many people, even Republicans and Obamacare opponents, claim prohibiting charging more or denying insurance for pre-existing conditions is a good part of the Affordable Healthcare Act. This may make sense from a compassionate point of view, but from a practical point of view it is the root of what is wrong with Obamacare. Democrats and Obamacare supporters claim allowing these people into insurance pools spreads the risk. That is disingenuous and shows a complete lack of how insurance is supposed to work. Insurance spreads the risk for qualifying events whether it be a medical problem as in health insurance or a car wreck covered under Automobile insurance. If you allow people who have already had a qualifying event to join a risk pool and have those events covered, that's not spreading the risk through insurance. It's redistribution of the wealth. Period. Allowing these sick people to join the pools without any exclusions or premium increases is what forced the hated mandate strategy. Democrats needed healthy young people in the pools with the sick. It also caused the Obama administration to write the regulations for grandfathered policies in a way that forced many of them to be canceled. They needed these peole in the pools with the sick. Even with the mandates and policy cancellations, Obamacare is still forcing premiums up. The expected higher premiums caused the writers of the law to put in subsidies of up to 400% of the poverty level. Then, in order to claim the law wouldn't explode the federal deficit, new taxes had to be levied, Medicare had to be cut and death panels had to be instituted. All these problems tie back to giving people with pre-existing conditions a heavily subsidized ride. The truth is 85% of Americans had health coverage they were satisfied with. A large portion of the remaining 15% were healthy young people who didn't feel the need for insurance. To sell the law, democrats love to trot out a cancer patient they claim can't get insurance. The truth is many of the people with pre-existing conditions are diabetic due to obesity, have serious heart of lung problems from smoking too many years or are alcohol or drug abusers. Is it fair or even logical to shake up the whole health care and insurance system because of a small percentage of the population?