"200 servers along with documents, cellphones and large quantities of cash"
Yep, but no guns.
600 armed officers seems a tad much for invading an ISP's premises, even if said ISP is located in a bunker. I mean come on, there's 450 of those guys who must have spent four hours just standing around.
Yes, it was a WWII bunker. That does not mean that it was defended like a WWII bunker. If it had been, I'm pretty sure that 600 cops might not have been enough, and the death toll would have been, as they say, catastrophic.
A much better option would have been to send a squad of 20 men, and keep a hundred as backup. If shots got actually fired, then bring in the army.
They made a pseudo-military operation out of a perfectly civilian one.