The possibility exist that there was a military/ border dispute between the Federation and the Romulans, and the Federation lost.
Rather than continue a conflict that they obviously weren't going to win, the Federation agreed to a Romulan generated treaty that placed them at an disadvantage.
I never considered that possibility--the Federation simply lost a small scale battle and were forced to sign on to keep the peace.
However, I get the notion that the Federation (Humans) are very different than humans today. They are very pacifistic and see having a military as an unwanted necessity.
Picard refused to call the Starfleet the military and later on DS9 they had a problem calling the Defiant a warship.
However like Anwar, I think they signed it because they had developed other ways of sensing them, even though it was nowhere near foolproof.