No President has ever been indicted. Him not doing what no president has ever done - come under indictment - does not somehow distinguish him in the other direction.
Presidents in previous times have been impeached or have resigned. They also did not exist in 2018 when the level of scrutiny and transparency is much greater than it would have been in the 1950's and such. The media, in those times, largely played along with the will of the government, and the population was much less critical. The ability for a lone individual to stand up and challenge a man of high authority like Kavanaugh, as Dr. Ford did, would not have existed in such times.
Today, just about anybody could pop up in the news and tell a story about Trump, and provide evidence for it, if they possessed any. Hell, they can do it even without any evidence.
There are objective standards and subjective observations for the transparency of an administration and party, including amount of public discussion on policies, voluntary disclosure and/or resignation of conflicts of interest, public insight into political decisions, and forthright discussion of policies. In all of these areas, this administration is not only lagging behind but is affirmatively the single worst administration in the post-WW2 era. That isn't changed if, at the end, Trump himself is not convicted of a crime. Because lack of transparency and contravention of political norms are not themselves crimes, the failure to prove a crime does not disprove their existence. Just like if ultimately Watergate didn't produce enough evidence to warrant an indictment, that wouldn't all of the sudden make the Nixon administration a beacon of transparency just because the press had a boner for them and hadn't been able to prove a crime - due in part to the administration's opaqueness. That's why your statement is silly and fallacious.
But Watergate
did produce enough evidence to warrant an indictment.
I have no reason to believe that Mueller isn't doing a good enough job to produce evidence of Trump's crimes if he has committed any. He seems like a man fit for the job and if he clears Trump of any wrong-doings, then there probably weren't any wrong-doings. If you think that he is incompetent, or if you think that America's institutions are dysfunctional, then you are free to think different. The media has a hard-on for this, so that won't be a problem. They will put on the pressure if no one else will.
The way that people are setting the table for themselves to act as if Trump is criminal, even if he is not implicated in any crimes, that, to me, is silly and fallacious. They would never employ such a hypocritical stance against "one of their own".
When Hillary was cleared of wrong-doings, and intensely scrutinized, without results, this was a sign to her supporters that she did not do any wrong, even if there was evidence that she did. I do not see why a Trump supporter should not think the same about "their man". For my money, he is definitely the most scrutinized, the most investigated president of all time, and if he walks away from all of it without a scratch, then he probably had a pretty damn clean record, at the end of the day.
As I said, Obama is the only one who has a similar claim, the rest of them, we'll never know what could have been dug up about them in modern times, with the level of media and public interest.