"Because" is an insufficient reason (that we're likely to hear from Democrats once it's obvious the President is a criminal), like a patriarch saying "because", with no real explanation. That's because it's power speaking to we, the people. They're telling us what to do, to put it short. What, we would have had a civil war during the 1970s? Let's say that's true: why then did the GOP go on to foster-division during the Reagan, Bush I and Bush II years? Ah, I see we're not being honest about it. The real reason is this: they and the DNC want to keep the imperial Presidency and keep it unaccountable to the public as much as they can. The problem is, they forgot that while you can do almost whatever you want, there are still political-costs attached. Eventually, the public won't have it. By wanting reelection (by stealing it) again in 2004, all the Bush administration did was give us all more-time to get them in. The first shall be last.
The neocons even attempted to take the powers of the Presidency much-further, under the auspices of Vice President Dick Cheney (Ford cabinet member). Demand trials, or a civil war will be inevitable. There wasn't any squeamishness during Clinton's hearings, but maybe someone was scared to pull that trigger. Don't want to give-up that good thing that both parties have-access to. We can take a trial of a sitting American President, we're not children. If we have to reorder the structure of the Executive branch, so what? It is to the shame of ex-President Ford and those who support this contention, and history will not be kind to them. Now, bury the ignominious-twit and shut-up, let's move on and put him behind-us. He was always beneath us, what a worthless-individual. Bottom-line: economic and political elites don't benefit from trials of politicians, but the public and the common good does. The choice should be simple after this realization.