In Settlers of Catan, I have always played that you can play a knight development card before your turn, which is obviously useful to get the robber off or your own hex before you roll the dice. Is this the same with all playable development cards? I have played lots of Catan but I have never raised this question with my friends before since I did not think there was any scenario in which it would be advantageous to play a different Development card before rolling.
However, consider this scenario:
I have 11 cards (6 ore, 4 wheat, 1 brick), 8 victory points, and the ability to build 2 cities next turn, giving me the victory. If I roll a 7, I will lose 5 cards, which will ruin my ability to build both cities and win on my turn. If, however, I play a Monopoly and take 8 arbitrary resources (say lumber), even if a 7 is rolled I will lose 9 resources but still be able to keep the 10 resources (4 wheat, 6 ore) necessary to build my cities and win.
Does anyone know if in situations like this it legal to play any playable development card prior to rolling?
Also, I still cannot see a benefit to playing a Road Building card prior to rolling. Anyone have any ideas?