They gave it a shot, but it wasn't good enough.
The reason it was not good enough is because this process , like many others in our government, is fundamentally broken. And sometimes there isn't a "process" at all to deal with the problems like this.
I mean, Trump's defense team technically had some sound arguments among their awful ones, using a big arsenal of lawyer tactics to get this dismissed. The case was "unfair", moved "too fast", and was a little undercooked.
The problem that Schiff and the House managers presented was more of an emotional plea that things are fucked up. There is a massive bug in that the President can stonewall an investigation indefinitely, and then use that hobbled case as a legal defense of unfairness). It is alarming, but not something that impeachment was very likely to solve. Could you say that our entire justice system gets reformed, even if the Senate voted to remove? No, I don't think so - and it would be curing a symptom, and not the disease.
These are Nixon's people. These are Reagan's people. They have spent decades, not repenting for past sins, but refining their process for getting away with it next time. So that their guy can't be taken down again. They started Fox News specifically for this purpose.
I feel resolved to make sure that we are heard this coming election. It's in our hands, and we cannot be asleep at the wheel again.