This article highlights the high costs for early retirees, but does not explain why many people are in that situation involuntarily.  To do that, you need to understand the negative impacts with employer provided insurance.  Or perhaps I should say government funded health insurance since employers get a tax deduction for most of the cost.  I was an IT consultant to the insurance industry for many years, and I have seen some of these impacts
It is important to realize that Obamacare (and any other plan that deals with non-employer funded insurance) is fighting an uphill battle.  The employer plans cover the vast majority of young, healthy individuals.  Many of the remaining people cannot work because they are ill or disabled.  By allowing the employer provided plans to cherry pick the best risks, the remaining pool is much more expensive. Obamacare deals with this by providing some government funding for the poorest people.  So, we have government tax credits funding insurance for working people, and government subsidies funding insurance for poorer people.  This leaves non working middle class people to pay very high premiums with no assistance.  This often means that the cost is unavoidable.
There is one obvious question that is not discussed.  Why would someone leave a job that provided insurance if they could not afford the insurance on there own.
This gets into another major problem with employer provided healthcare cost.  Many people do not realize that the cost your employer pays is based on the health of the employees.  A company that employees young health individuals will be offered a lower premium than a company that has older less healthy employees.   With a large company, the risks are spread across a large number of people,so the impact is less.  However, for a smaller company, the health of each employee can impact the cost and availability.
For instance,  a friend of mine started her own company.  It did very well and grew to about 40 people.  Then, my friend developed brain cancer which was very expensive to treat.  At the end of the year, the insurance company refused to renew the policy for the entire company.  No other insurers would touch it.  She would up selling the company to Microsoft, and declaring bankruptcy.  Fortunately, she was able to get a job at another company with a much bigger pool of employees.
This example highlights an extreme example, but the impact of health on the cost of employer provided insurance is much more insidious.  Most people have heard that there is age discrimination because older people are at the peak of there earnings.  What they do not realize is that having too many older worker can drive up insurance cost for all of the employees.  This provides a strong incentive for companies to get rid of older employees who tend to have higher medical costs.  
The vast majority of people that I know who have retired early did not plan to retire early.  Like many, I had planned to work until I reached 70.  Instead, I was laid off at 63.  Others I know were offered early retirement packages, but it was clear that if they did not take it, they would probably be fired.  It is very difficult to find a new job for the same reasons.

This is only one of the problems with employer provided healthcare. The US will never have good affordable health care until we stop having employers purchasing the health coverage for their employees.