It effectively is a fine, but it's not a criminal penalty, so it's kind of like an opt-out fee that's significantly cheaper than most of the supposedly affordable plans. (Which are extremely expensive even at the low-end where they're completely useless with $10,000 deductibles.)
I think you are dramatically underestimating the cost of getting "actually sick" if you think a $10,000 annual out-of-pocket maximum is "completely useless". Not to put too fine a point on it, but $10k could be a mere couple hours of care in the ER.
Also, there are cost-sharing reductions which would reduce that $10k significantly depending on your income.
If you do find yourself in need of actual medical care but without any insurance, the workaround is simply you will have to move to a new state, which will allow you to sign up outside of open enrollment periods.
The maximum out of pocket costs under the law is $6850 for an individual and $13700 for a family.
Regardless, the law is the law and it's undoubted that the folks who choosing not to do their legally required part and maintain health insurance will immediately jump on a plan if they happen to need care. Bunch of selfish jerks.