It's only for a GmbH and the minimum liability. You can also found a UG but then your private money is on risk.

That's the minimum deposit. You keep the money 100%, and can then start investing it.

It serves as basic legitimacy.

As operating capital. Doesn't seem too unreasonable for most industries. Maybe it is high for consulting and software. But with anything you need to buy inventory, machinery, rent space and so on. It makes perfect sense to demand.