So why don't you change it?

Edit, I did it for you.

A very good question. Some refer to movies by year of production, others by first public screening (festivals) others prefer theatrical release or first airing on the original network (for tv series, but what about series with multiple original networks? like german / australian coproductions?) Maybe it is best to collect all the dates with proper tagging of what the date represents. Then everyone can pick the right date for their use case.

Some movie are released for DVD/BlueRay immediatly and does not have theatrical release dates. (Who said dumb movies ? ;-))

Check out this thread for an official reply from Travis (and some thoughts from other users).

To sum up the official reply: There is a possible solution to this issue, but it is unclear whether it is a priority or not. Low priority is my guess.