If you want to see what happens if we remove trial by jury, look at magistrates courts. Whilst they are only supposed to convict if the prosecution has proved its case beyond reasonable doubt, the reality is that they operate to a much lower standard of proof. "I preferred the police officer's evidence" is something you will hear far too often. If I am ever charged with an offence and have the option of a jury trial, I would definitely take it as they are more likely to operate to the required standard.
See also Denning dismissing the Birmingham Six's civil claim against the police - "If they won, it would mean that the police were guilty of perjury; that they were guilty of violence and threats; that the confessions were involuntary and improperly admitted in evidence; and that the convictions were erroneous… That was such an appalling vista that every sensible person would say, ‘It cannot be right that these actions should go any further’." Of course, the police were guilty of perjury. They were guilty of violence and threats. The confessions were involuntary and they were improperly admitted in evidence. And the convictions were erroneous.
There are cases where the defendant is clearly rolling the dice, hoping that the jury get it wrong. However, there are also cases where the defendant is hoping that the jury is more in touch with current mores and attitudes, so will give them a better chance of a correct verdict. And, of course, juries can acquit defendants when they don't agree with the law - something which a judge would never do. See, for example, Clive Ponting who leaked papers about the sinking of the General Belgrano to a Labour MP. A judge would undoubtedly have convicted him. The jury, to the fury of the government, acquitted him.
Jury trials are an important right and a protection against an authoritarian state. I am disappointed that so many are keen to throw away this protection. As David Lammy said 5 years ago, "Jury trials are a fundamental part of our democratic settlement. Criminal trials without juries are a bad idea."