AMEX Blue Card Credit Limit?

I have a Discover with a limit of 11,800, and a Working ets with a limit of 19,800. When I first applied for the iscover in 2005, even they gave my initial limit of $8000, and ive had my working ets for 22 years. I applied for a Amex Blue and only got a limit of $2000. Why do you guys think this might be?