It's unfortunate, since many women need birth control for controlling their periods as well. As Imprint mentions, it wouldn't cost the company extra-- they're just denying a kind of treatment due to personal beliefs. As much as I'm Catholic and understand the discomfort some have towards birth control, it's not really fair towards these women to have less options.

If you're a guy, you may not automatically understand the awful inconvenience of having a heavy period, especially while working.
Without birth control:
- With some women, even a large pad won't carry you til 1pm
- Basically, your day would consist of changing your pad every 1-2 hours(if you remember to), just so you don't bleed on yourself until your next meeting.
With birth control:
- you can last on 1 pad for much longer, like 6-10 hours at least
- also allows you to "schedule" your period, basically decide if you want to deal with it over the weekend or weekdays. Obviously, most working women would go with the weekend.

Then this isn't even covering how some women take birth control pills in case of rape-- out of fear, and precaution.

Yeah, they could pay out of pocket, and those that need it will have to. But by not supplying it, they're making the working lives of these women harder than it has to be.