What good is 'Friendship' ?

It is easier to convince a friendly nation to attack another for a small sum of gold/lux/resources.

What good is friendhip? Let's ask John de Lancie:

Link to video.
And in Civ terms, it maximizes prices you get for goods, makes it more likely for you to be the favorite of an AI (they will back you up in case of wars/denouncements and will get angry with civs hostile towards you), makes AI more inclined to help you in need and decreases the chance of out-of-the-blue hostilities. And ofc, in BNW, it allows you to trade cash and sign science agreements. Gotta also mention that DoFs can create chains and make the world a better place, or at least a duller one.

In previous civilization games (actually i'm not sure if it was mods) friendly civs often give you spare resources and gold without asking them, and warmongers actually asked for tributes. Now look at civ 5.

Beaver79 said:

Your friend can also ask you to denounce another civ. If you don't you friend automatically denounces you.

Click to expand...

You mean your friend MIGHT denounce you.

Had this happen to me too. Was quite a shock because when I refused before, he didn`t do anything just went `meh`and we remained friends. So I guess it depends how much he likes you whether he denounces you or not after the request.