Young people are the poorest age group. Middle aged and older people are the wealthiest age groups. Why should relatively poor young folks continue to pay more and more and more to subsidize their relatively rich elders?
So a lot of people heat their homes in the winter with natural gas. In the summer, natural gas bills are low. In the winter, they can be very high.
You can sign up for a payment plan that evens out the costs. You pay more than you normally would in the summer, and less than you normally would in the winter. The monthly charge doesn't change much all year long.
This plan makes it much easier to budget for expenses.
It turns out this approach works well for health care, too. Pay about the same in the summer (when you're young) and in the winter (when you're old).
You see, many young people just aren't very good at planning for the future. For example, many old people would be homeless, and starve on the streets (and die) when they got old, without something like Social Security. The system actually works very well, despite right-wing lies that it doesn't (the only problems are congress borrowing money from Social Security for non Social Security related things).
So the same proven approach is being applied to health care. This is a good idea.