It's way harder to defend American computer networks from foreign hacker attack if one of the conditions is the networks have to be open to NSA surveillance.
As a nation, we need to prioritize defense over offense. Right now, the NSA and U.S. Cyber Command have a strong interest in keeping the Internet insecure so they can better eavesdrop on and attack our enemies. But this prioritization cuts both ways: We can't leave others' networks vulnerable without also leaving our own vulnerable. And as one of the most networked countries on the planet, we are highly vulnerable to attack. It would be better to focus the NSA's mission on defense and harden our infrastructure against attack.