negative example is in my opinion arcarea, that quickly moved from long-negotiated peace to war, even if she was not party directly involved in ga-cathay troubles, in my opinion just to use favorable disposition of military forces. ordering attack and than declaring war 15 minutes before turn-change is one of my the least respected things in the whole game, and falls into similar category. there is no any rp-ing justification for use of diplomatic buttons for military tactical purposes, in my personal opinion, that just leaves bad taste.
Not everybody was surprised at this, to say the least. Maybe you're not hanging out in the right circles?
The problem with your proposal is that rulers would be forced to drop the alliance at the first sign of tension. It is normal that alliances keep existing on paper even when tensions exist, and get torn apart only at the last minute.
