Yaawn. Way to completely run away from the point like it’s on fire. It’s not about the calendar of one culture, it’s about dealing with the calendar of a culture that’s other than the people trying to navigate it. How do you explain to a group of people who don’t know Chinese history when something happened in China? You can’t use the Chinese calendar, your audience doesn’t understand it, if you use the calendar of your audience you’re projecting their culture on the Chinese event you’re trying to discuss, so instead you come up with a common (oh look there’s that word you foolishly insist has no meaning) reference structure that can span both culture.
If a person uses the Gregorian calendar, which I daresay includes the majority of the human race today to one extent or another, then they know this is 2011. They would also know it's 2011 AD, because that's the convention that's been adopted, to superseded the Mayan calendar, the Julian Calender, and for official purposes at least the Chinese Calendar. Like certain abbreviations such as etc, AM and PM, we use these shorthand designations even if in some cases it is long after most people have forgotten their roots, and exact meaning. So anyone familiar with the Gregorian calender would know that 200 BC is 2211 years ago.
The fact that one may use a calender based on a European estimation of the birth of Christ while changing the abbreviation, makes it no more relevant or "in common" with another culture who may not be Christian in orientation. If the United States replaced the Constitution with the Koran and Sharia, and called it "Common Law," it would still be based on the Muslim faith.
Now, if I call that structure the "Great wall of China" instead of 长城/万里长城 how am I not projecting my culture on their historic treasure? How chauvinistic would I be to refer to its length in miles? After all, over there it's the Ten Thousand Li Long Wall.
If we want to be more inclusive, then it would make sense to revise the calender altogether, and start from 0 in say 3200 BC, or whatever is estimated to be the earliest written record. Thus, we are now living in 5211. Now THAT makes sense.
By the way, the BBC itself states “The Corporation’s religion website states that it opts for the “religiously neutral” Common Era and Before Common Era, rather than Anno Domini (the year of Our Lord) and Before Christ” so you’re reasoning does not apply to this decision.