i think impeachment serves a number of nonsymbolic purposes. Most immediately, without impeachment Trump would pardon the Capitol invaders. With impeachment, he can't do that. Second, it sends a message that instigating a seditious violent attack on Congress is not going to be ignored. Third, if convicted, he is barred from running in 2024 and can't use that possibility to maintain his hold on the Republican Party. Fourth, and perhaps most important to future American security, if convicted he is not entitled to national security briefings.
In terms of downside, I don't see the impeachment making Trump's core any angrier than they already are. In a way, it will be a step forward to have their anger at least somewhat grounded in reality, rather than Trump's lies of a stolen election and QAnon's insane conspiracies of satanic child traffickers and blood drinkers. On the plus side, a chance to present the evidence of Trump's undemocratic sedition in a hard-to-ignore setting. the only downside I see is distraction from the business of the Senate.
I am proud that my Democratic Party hasn't chosen AF's expediency and appeasing of seditionists, just as I am glad that they didn't surrender their moral position and follow his 'pragmatic' call to abandon the pursuit of equality, especially for the LGBTQ community. A party should stand for something bigger than political tactics. That is the path to irrelevance and moral loss. Biden won, without abandoning Dem's traditional efforts to protect the weak and minorities.
I also think after something as anti-American and evil as the white supremacist's attack on the Capitol, it is salutory to require each Republican Senator to take a recorded vote on Trump's actions. I only wish that the House had included an article of impeachment regarding Trump's interference with the proper function of state election officials -- the Raffensperger tape would make an excellent Exhibit #1.