From: United Kingdom
War weariness is a problem because you automatically declare war back on somebody who has declared war on you.
I mean, this is my war minister. He declares war when I want to. However, everytime some insect on the other end of the galaxy decides to declare war on me, and I have no chance to beg for peace, my war minister automatically stands up and says: "Ok, and we declare war back on you!"
What ever happened to the option B:
"Fine, your race has declared war on me. I opt to do nothing, I will just sit around and defend my colonies."
Then the enemy race would be at war with me and suffer war weariness. However, mine doesn't. I can't attack him, only defend, because officially I didn't declare war back on them!
If this isn't fixed, then I will soon exterminate a whole 20 advanced alien species just with 1 colony ship. How? I build a colony ship, send it to the border of the galaxy where it cant be found. Then I declare war on everyone! They can't find me, yet the more time passes the more unhappy their colonists become. They can't just stop the war because I refuse to give peace! It's just as simple as that. Sooner or later the WW grows to inacceptable levels, everyone of their planets will have 0% tax and still rebell. Even the most advanced planets will bail out after 20 years of war weariness. They can't pay maintenance for their ships and bases anymore. When they are 1 Million credits into debt, their civs all collapse, what will they do against this exploit? LOL. Looking back on the events 30 years later, my colony ship goes to the next nearest planet and starts to build an empire without anyone left. You win!
That's what happens when somebody can control what your own military minister says.
Try it; you'll lose your colony long before that happens.
If someone declares war on you; you aren't declaring war on them. They declare war against you, so now a state of War exists between you whether you like it or not.
I'm lots of countries throughout history would've loved it if they could ignore the negative effects on a population of being at war purely because they were defending themselves. Sooner or later people get sick of being bombed and of losing their families in the fighting and just want to get on with life.
You can sue for peace immediately the war starts if you like and the diplomacy screen will show you what kind of value you need to be offering before the race that just started a war with you will consider a ceasefire. Although considering you're being a bit of a pushover, the price for peace might be quite high.