"I don't get the need for the BCE/CE calender."

That's simply because that some of us, while making use of the Gregorian Calender for civic convenience, refuse to acknowledge that G-d was ever actually 'Born', or that he ever actually assumed a corporeal corruptible form.
In Israel, many Jewish religious schools and institutions don't use the Gregorian Calender at all in dating their document, but rely solely on the Hebrew calender.
As for the Hebrew year 5770, the Hebrew calender dates itself from the supposed moment of Creation, when G-d said: "Let there be light...'
While I don't want to get into a debate as to the truth or non-truth of when Creation actually took place (and remember that G-d NEVER intended that the Torah be considered as a Scientific Textbook, [and therefore one in which no generation before Charles Darwin could have possibly understood].  Rather, the Torah, as handed down to Moses, was and is a Holy Constitution, set before a nation, a body politic, so that that nation might live as a Holy Nation, and that every act of human endeavor would be a sanctification of His Name).
I DO believe though that it is interesting that the Hebrew Calender seems to date from the beginning of Recorded History.
dph

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