We had it before the ACA's mandate. 85% of group health plans provided it. Non-profits in all 50 States and many local governments make it available to those who can't afford it. The cost is not prohibitive even for those without insurance who don't wish to avail themselves of the aforementioned options.
You're assuming all birth control methods are created equal. They aren't.
The pill is a comparatively poor method in terms of success rate (roughly 9%/year failure rate and needs to be taken religiously every day) compared to more recent methods, such as IUDs (0.2-0.8% failure rate, depending on type. Basically foolproof as they're insert-and-forget for 3+ years) and implants (0.05% (this is actually better than the success rate for tubal ligation), insert-and-forget for 4 years).
The mandate expanded the state of things from "Oh, you're poor, so you get the failure-prone pill because it's cheap" to "Take your pick of any method, they're all covered", which is a good thing. Saddling people who can least afford a child with the most failure-prone method for preventing that is a recipe for disaster.