The Romulans appear to be quite willing to sign similarly hobbling treaties - they agreed not to develop polaric ion weapons ("Time and Again") and steered clear of subspace weapons, too (ST:INS). It also appears they never developed metagenic weapons, even though their know-how must have been decades or centuries ahead that of the Cardassians ("Chain of Command").
The Trek universe is full of superweapons. Just like in the real world, those are usually the most powerful and effective when not
used - and thus the most cost-effective when not built in the first place.