It's worth noting how historically bad the winter was in the Midwest. It was simultaneously the third-coldest and third-snowiest winter in Chicago history. Chicago hadn't seen temperatures that low in 20 years, and hadn't seen that much snowfall in 35 years. This was truly a once-in-a-generation type of winter, and not something you plan for on an annual basis.
That said, there could have been plenty of other things that contributed to the delayed opening, but if ever there was a year that weather was a perfectly valid excuse, it was this year.