Why would Shepard even be chasing Saren though? The only reason why Saren needed the beacon on Eden Prime was because the data he had was incomplete, and even then the Eden Prime beacon only had a partial transcript of the information he needed.
If Saren could have unrestricted, Spectre access to a fully functional beacon he would have had no need to attack Eden Prime, Shepard would have had no pressing need to become a Spectre to chase him, and Saren would have located the Conduit without any opposition.
What does that have to do with the artifact?
If Shepard used the artifact, and its possible that it could be avoided till a later time, she/he would just pass the information to the Council and let them deal with it and Shepard would continue with chasing Saren
I'm not excusing the Asari for their actions in ME 3; they mucked up the situation pretty badly for everyone; but their hiding of the beacon pre-Reaper invasion was in no way a species damning sin; hypocritical and selfish yes, and something that would cause a galaxy-wide scandal if revealed; but there was no way to know that the information they were hoarding was crucial to defeating these giant robotic cuttlefish that lived out in dark space.
I'm not saying they did know what the artifact contained.
but my point is that the Asari are not the worst war criminals in the galaxy.
I agree they're not war criminals. The problem is convincing everyone in the galaxy. If I'm on Earth and my family is killed and later found out that the asari failed to reveal information that could've made a difference, you bet I would blame the asari. If I was to ever visit the Citadel and see an asari, I would kill that asari. I might not be the only one who would do that, but I'm sure a lot of folks would be giving the asari the evil eye
Every species made some really stupid decisions in the war, the Salarian Dalatrass' hissy fit about the Genophage and her refusal to send aid if it was cured,
Did it cost lives?
the Quarian's starting a war with the Geth on the cusp of a Reaper invasion,
I look at that as a case of dumb and dumber. The Quarians attacking the geth and geth for siding with the reapers.
humanity's 'champions' staging a coup of the Council and giving the Reapers access to the Citadel, etc.
I would've switched that mission and the Thessia mission. I would have Thessia first and then after Rannoch have the coup that way it explains why Cerberus attacks the Citadel
The TIM attacked the Mars Archives and stole a copy of the Crucible plans, and that information was being divulged between the Alliance and Liara;
He would not of gotten that information had Liara downloaded the plans immediately to Hackett. She did say she found something that could wipeout the reapers. How does she know that? If the plans told her that, she would've seen that Thessia holds another piece of the puzzle.