The overwhelming majority of those intercepts aren't in English, so you need linguists to translate the messages. There are some 49 languages in Afghanistan alone, so finding people to translate them all is a problem. Throw in dialects of Arabic and Farsi and the problem just keeps getting bigger. This source lists citations from over 1000 languages worldwide, with references to perhaps a total of 6700 languages.

I rather doubt any of the messages came right out and provided specific details about an impending attack, either. The terrorists simply aren't that stupid, Hollywood fantasies to the contrary.

Actual intelligence work is trying to put the pieces together to provide a warning, but there are millions of pieces per hour and they keep moving. The pieces are almost always in foreign languages (how many Pashtoon speakers work for the US government, anyway) and are cryptic, to say the least. You can pretend otherwise but you'd be just as deluded about this as you are about most other things.