The difficulty does little imho for the campaign dullness, the basic thing is still that the AI is flawed.

I might be unlucky, but as for the most action on the campaign map and in battle, all settings on medium seemingly makes the AI do more stuff.. on any other setting on my computer, the AI does very, very little. In my last campaign, as Sweden again, Poland declared war on me without me really starting wars, I hopped over and found city after city without garrisons, on VH/VH (I'd given the baltics away to Spain for fun.. :P), then Russia declared war, and sent half a stack army over to the baltics, and the rest of Russia was undefended and quickly fell from a invasion via Finland.... .. .. . This is where I quit.

Glaring issues like that doesn't help.

And yes, will look forward to the income/cost changes, on the last few campaigns I make myself not go for the trading regions, because the later 50K income make things even easier.. :D