The purpose of a no-knock warrant
Yes, there is an advantage in safety to the officers, as compared to entry just after knocking or long after knocking. True enough that the best tactical advantage, in terms of safety, is to surround and ask for surrender, but this consumes large amounts of time/manpower/money in conducting a standoff/negotiation until surrender occurs - it simply isn't practical to utilized a technique that would result in standoffs a significantly high percentage of the time; hence the dynamic entry. That said, two points:
1. No-knock warrants, as mentioned, are flat wong IMO as well, and should never happen in our society. If I was a magistrate, I would never approve one - but they do, and the SCOTUS has OK'ed it.
2. Notwithstanding the slight tactical/safety advantage mentioned above and the excuse to gear up gestapo-style and get an adrenaline rush, the MAIN reason for them, as compared with the knock & announce a few seconds before entry, in the minds of the LEOs/LEOAs, is to PRESERVE THE EVIDENCE. They are primarily concerned with making the bust for their own glorification/justification; thus, they are primarily concerned with keeping the cocaine out of the toilet drain, which doesn't take long for the suspects to do. Ask the LEOs - that's why they do it - far and away the most important reason. They are under tremendous pressure to make a bust to further the captains career or whatever.
Bankrupting the state - mostly just an expression on my part, but good question come to think of it - obviously, taxpayers foot the bill in the long run, but if the plaintiffs obtained judgment and the state was involvent (did not have enough liquid assets to pay the claim), they certainly might seek bankruptcy protection - I know that municipalities (cities) can and do from time to time. The state's liability is limited typically under the tort claims acts of the various state, usually to 100K or 125K for negligence; hence it's usually not an issue. I'm not aware of a state which has ever filed bankruptcy, nor do I know if it is even theoretically possible, but I'm quite sure a state would try to file bankruptcy if it had claims which it was unable to pay, and had valuable needed assets being attached to satisfy them... As far as the general public policy of whether it's a good idea to hold the state accountable financially - well, it definitely is, because then the taxpayers get mad that they have to foot the bill (and rightfully so), and therefore vote out the idiots/scoundrels/nazis whose policies led to the wrongdoing. Not ideal, but something has to provide incentive to get rid of the pond scum when neeeded.