Do Raging Barbarians make it harder for the AI?

Solution 1:

It really does depend on what difficulty you're playing at.

http://www.civfanatics.com/civ5/difficulties

The second table found at the above link is a comparison of the bonuses the AI get at different difficulty levels.

For example, at Prince (which can be considered 'normal') the AI gets a 60% bonus vs. Barbarians. This applies at all the higher difficulty levels too. So more barbarians will have a less pronounced effect on AI than on you, because they are 60% better at dealing with them.

By far the best way to make the game more challenging is to increase the difficulty level. At Deity difficulty level, AI start with two workers and a scout, amongst other things.