In a way you answered your own question: the 2% comes to not have to spend a lot of fixed money in a one blow, like the case here with 100B.Instead you spend constantly and improve, after all defence is an investment and that investment is not lost even if you don't have any wars.(unless you spend on active training and decades pass w/o wars)

Referencing my previous post with the link for the politics of 2%, there are a lot of things Germany frankly is really behind when it comes to military: Poland for example has stronger military relatively speaking if you compare the manpower, reserves, total population and military hardware.

The money indeed goes to the mil. industrial complex which is undesirable,that's why i'm skeptical about this, but at the same time: do you take the chances when a nutjob like Putin keeps daring you? There's no good answer, only compromise

I don't want to sound like a broken clock, but Germany could have used the investments of NS2 into energy independence(more nuclear, electric,etc),NATO contribution, or infrastructure.Socialistic policies are also good, but there's higher volatility in terms of what you get, and if you want to actually put socialistic policies in practice, follow the hungarian long-term model, not welfare-state for everyone: Merkel probably learned this the hard way, and the barely-not-recession numbers show that.