The principle that officers should be suspended on full pay pending investigations is right but there are examples where it has helped people play the system - for example, to delay hearings on the grounds of sickness. Then people retire on medical grounds and because - unless there are criminal proceedings - the inquiry is ended because the biggest sanction that someone would lose their job has gone.
Hillsborough (the football tragedy for those outside the UK) is another example. It took so long to launch an inquiry that all the officers there on the day had retired. A decision was taken that none of the officers present would face prosecution. Six officers in charge of the decisions the police made at the match were eventually prosecuted but I think only one ever went to trial and was found innocent, much to the distress of the families.
Despite this, I don't see an alternative to suspending people on full pay. I am just pointing out that it can be abused.
Systems to vet people joining the police can never be 100% foolproof but I expect higher standards of the police because of their role in society. I also expect them to investigate allegations about individual officers' conduct fully. Strikingly, in the example given by IDanielRadcliffe, the officer was not suspended at all and the two women victims said an investigation by another police authority was inadequate. Although there are different standards of proof, the women have received compensation from the Criminal Injuries Compensation Authority.