Why is it okay that Activision jacks prices up on PC Modern Warfare 2 yet Valve are suddenly monsters for their European prices?
Why, that is the whole point. See, Valve aren't monsters, and neither are Activision. However, you want to depict Activision as evil overlords while you are quite ready to excuse even worse conduct from Valve simply because you like them better.
You can't both approve and disapprove of shady business activity, you either like it or you don't, you can't just make excuses for it when one company is involved and then point out how absolutely devilish it is when another company does it.
Why is it okay that Activision do whatever it wants, ruin as many game series as it wants, and gives customers [censored] deals and thats OKAY as long as it tells us what its doing?
Because as long as the players have the facts, they can make an informed decision. You can choose not to pay the increased prices, or you can choose to do so, but there is no excuse for not knowing about them.
Activision is systematically demolishing its franchises and its just okay as long as they tell us?
Well, it's their property. If they can't do as they wish with it, who has that right?
Its as simple as this: I hate Activision. I'd hate them regardless of what they tell us, because I can see poor quality and bad customer service for myself, and that's all I need to see.
And as some people here are pointing out, perhaps hatred isn't really the most fitting or appropriate response to a small increase in prices.