See, e.g. here I'd agree with you totally: almost the entirety of that money spent on the militarization of police is worthless, or, worse, actively harmful. You don't need to make bullshit arguments to support it. Indeed, you weaken people's perceptions of the strength of the case when you give them bullshit arguments.
And the average clearance rate for murder is around 60.
Given that police prioritize some crimes over others, one should be careful in using the stats for things they don't place a priority on as a basis to pass judgement. If the violent crime rate could be lowered for example, say by removing the ability of a violent gang to operate (i.e., arrest and convict them), this frees up time to go after other crimes. We are looking at the current equilibrium achieved as a result of all their efforts, not some law of nature that happens either way (i.e. fixed clearance rates).
The point is that we should take the massive amount of funding that police receive in the US ($5.1 billion of which has gone towards military vehicles and equipment through the DOD 1033 program) and reallocate it to strategies which extend to people other options beyond a cycle of crime and punishment.